KR20170063887A - High-molecular compound, intermediate composition, negative electrode, electrical storage device, slurry for negative electrode, method for producing high-molecular compound, and method for producing negative electrode - Google Patents

Abstract

The polymer compound used as the negative electrode binder of the electrical storage device is a compound in which polyacrylic acid is condensed with a polyfunctional amine represented by the following general formula (1), Y is a linear alkyl group having 1 to 4 carbon atoms, Or an oxygen atom; and R 1 and R 2 are each independently a single or plural hydrogen atom, a methyl group, an ethyl group, a trifluoromethyl group, or a methoxy group.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer compound, an intermediate composition, a negative electrode, an electric storage device, a slurry for an anode electrode, a method for producing a polymer compound and a method for manufacturing an anode electrode, METHOD FOR PRODUCING HIGH-MOLECULAR COMPOUND, AND METHOD FOR PRODUCING NEGATIVE ELECTRODE

The present invention relates to a polymer compound used as a negative electrode binder of a power storage device, an intermediate composition of the polymer compound, a negative electrode, a storage device, a slurry for negative electrode, a method for producing a polymer compound, and a method for manufacturing a negative electrode.

BACKGROUND ART As a product using a secondary battery, a portable device such as a cellular phone or a notebook computer is widely used. The secondary battery has attracted attention as a large-sized power source for electric vehicles.

The electrode of the secondary battery is composed of, for example, a current collector formed of a metal material such as copper or aluminum and an active material layer bound on the current collector. Generally, the active material layer includes a binder as an electrode binder for binding an active material to a current collector. In recent years, the use of polyacrylic acid, which is an inexpensive polymer compound, as an electrode binder has been attempted. Patent Document 1 discloses a binder for electrodes comprising a lithium salt of polyacrylic acid or a sodium salt of polyacrylic acid. Patent Document 2 discloses a binder for electrodes comprising polyacrylic acid and polyethyleneimine. Patent Document 3 discloses a binder for electrodes comprising polyacrylic acid and an amine compound.

Japanese Laid-Open Patent Publication No. 2009-080971 Japanese Laid-Open Patent Publication No. 2009-135103 Japanese Patent Application Laid-Open No. 2003-003031

The present inventors have found that a polymer compound obtained by condensing polyacrylic acid and a polyfunctional amine having a specific molecular structure is useful as a negative electrode binder in a power storage device such as a secondary battery. Accordingly, an object of the present invention is to provide a polymer compound useful as a negative electrode binder of a power storage device, an intermediate composition for obtaining the polymer compound, a negative electrode using the polymer compound as a negative electrode binder, a storage device, and a slurry for negative electrode It is on. It is another object of the present invention to provide a method for producing the polymer compound and a method for producing the negative electrode.

According to a first aspect of the present invention, there is provided a polymer compound used as a negative electrode binder of a power storage device. Wherein the polymer compound is a compound obtained by condensing polyacrylic acid with a polyfunctional amine represented by the following general formula (1), Y is a linear alkyl group having 1 to 4 carbon atoms, a phenylene group, or an oxygen atom, Each independently represents a single or plural hydrogen atoms, a methyl group, an ethyl group, a trifluoromethyl group, or a methoxy group.

[Chemical Formula 1]

The polymer compound preferably has an acid anhydride structure.

According to a second aspect of the present invention, there is provided a polymer compound used as a negative electrode binder of a power storage device. The polymer compound has a cross-linking structure connecting carboxylic acid side chains between a chain structure formed of polyacrylic acid and a chain structure or a chain structure, and the cross-linking structure is represented by the following formula (4), PAA represents a chained structure composed of polyacrylic acid, X represents a structure represented by the following general formula (5), Y represents a hydrocarbon group having 1 to 10 carbon atoms A straight chain alkyl group of 1 to 4 carbon atoms, a phenylene group, or an oxygen atom; and R 1 and R 2 are each independently a single or multiple hydrogen atoms, a methyl group, an ethyl group, a trifluoromethyl group or a methoxy group.

(2)

(3)

The polymer compound preferably has at least a crosslinked structure of the general formula (2) and the general formula (4) or a crosslinked structure of at least the general formula (3) as the crosslinked structure.

The polymer compound preferably has an acid anhydride structure.

According to a third aspect of the present invention, there is provided an intermediate composition of a polymer compound used as a negative electrode binder of a power storage device. The intermediate composition contains a polyacrylic acid, a polyfunctional amine represented by the following general formula (1), and a nonaqueous solvent to form a liquid phase, Y is a linear alkyl group having 1 to 4 carbon atoms, a phenylene group, or an oxygen atom , R1 and R2 each independently represent a single or plural hydrogen atom, a methyl group, an ethyl group, a trifluoromethyl group, or a methoxy group.

[Chemical Formula 4]

In the above intermediate composition, the compounding ratio of polyacrylic acid and polyfunctional amine is preferably such that a mixing ratio of carboxyl groups in polyacrylic acid to one equivalent of amino group in polyfunctional amine is 15 equivalents or less.

In the above-mentioned intermediate composition, the compounding ratio of polyacrylic acid and polyfunctional amine is preferably a compounding ratio of 1.5 to 15 equivalents of carboxyl group in polyacrylic acid to one amino group of polyfunctional amine.

According to a fourth aspect of the present invention, there is provided a method for producing the above-mentioned polymer compound, comprising the steps of: heating a polyacrylic acid and a polyfunctional amine represented by the following general formula (1) Wherein Y is a linear alkyl group having 1 to 4 carbon atoms, a phenylene group, or an oxygen atom, and R 1 and R 2 are each independently selected from the group consisting of a single or plural hydrogen atoms, a methyl group, an ethyl group, a trifluoromethyl group, It is time.

[Chemical Formula 5]

According to a fifth aspect of the present invention, there is provided a method for producing a polymer compound, which comprises heating the intermediate composition at a temperature of from 150 캜 to 230 캜 after preheating the mixture at a temperature of 40 캜 to 140 캜 Method is provided.

According to a sixth aspect of the present invention, there is provided a method for producing a polymer compound, which comprises heating polyacrylic acid and a polyfunctional amine represented by the following general formula (1) at a temperature of 180 ° C to 230 ° C , Y is a linear alkyl group having 1 to 4 carbon atoms, a phenylene group, or an oxygen atom, and R 1 and R 2 are each independently a single or multiple hydrogen atom, a methyl group, to be.

[Chemical Formula 6]

According to a seventh aspect of the present invention, there is provided a process for producing a polymer compound, which process comprises the steps of preheating the intermediate composition at a temperature of from 40 캜 to 140 캜, Heat it.

According to an eighth aspect of the present invention, there is provided a negative electrode of a power storage device. The negative electrode includes a negative electrode binder containing the polymer compound and a negative electrode active material. The negative electrode active material includes a carbon-based material capable of absorbing and desorbing lithium, an element capable of alloying with lithium, and an element capable of alloying with lithium And at least one member selected from the group consisting of compounds having

The negative electrode active material in the negative electrode is preferably at least one selected from the group consisting of a silicon material obtained by decalcification from CaSi ₂ , Si, and SiO 2 _V (0>v> 2).

According to a ninth aspect of the present invention, there is provided a power storage device comprising the negative electrode and a non-aqueous electrolyte.

According to a tenth aspect of the present invention, there is provided a negative electrode slurry for use in manufacturing a negative electrode of a power storage device. The negative electrode slurry contains the intermediate composition, the negative electrode active material, and the solvent, and the negative electrode active material contains a carbon-based material capable of intercalating and deintercalating lithium, an element capable of alloying with lithium and an element capable of alloying with lithium ≪ / RTI >

In the negative electrode slurry, it is preferable that acetylene black is contained and the 50% particle diameter of the acetylene black is in the range of 0.35 to 0.75 mu m.

According to an eleventh aspect of the present invention, there is provided a method of manufacturing a negative electrode of a power storage device, comprising the steps of: forming a negative electrode active material layer on a current collector using the negative electrode electrode slurry;

In the method for producing the negative electrode, the negative electrode slurry may be a negative electrode active material, a silicon material obtained by decalcification from CaSi ₂ , at least one selected from Si and SiO _V (0 >v> 2) Is preferably contained.

According to a twelfth aspect of the present invention to solve the above problems, there is provided a negative electrode binder containing the polymer compound.

According to a thirteenth aspect of the present invention, a method of manufacturing a negative electrode of a power storage device is provided. This manufacturing method is characterized by comprising an active material layer forming step of forming a negative electrode active material layer on a current collector by using a mixture containing the intermediate composition and the negative electrode active material and a step of subjecting the negative electrode active material layer to heat treatment to condense the polyacrylic acid and the polyfunctional amine .

In the above production method, in the condensation step, the negative electrode active material layer is preferably dried and heat-treated.

According to a fourteenth aspect of the present invention, there is provided a polymer compound having a first crosslinking structure derived from a polyfunctional amine represented by the general formula (1) and a second crosslinking structure derived from another polyfunctional amine .

According to a fifteenth aspect of the present invention, there is provided a polymer compound used as a negative electrode binder of a power storage device. The polymer compound is a compound obtained by condensing polyacrylic acid with a polyfunctional amine represented by the following general formula (1) and a polyfunctional carboxylic acid.

(7)

In the polymer compound, it is preferable to further have a crosslinking structure derived from both the polyfunctional amine and the polyfunctional carboxylic acid represented by the general formula (1).

According to the present invention, the characteristics of the power storage device are improved.

Hereinafter, embodiments of the present invention will be described in detail.

The polymer compound of the present embodiment is a compound in which (A) polyacrylic acid and (B) a polyfunctional amine are condensed.

(A) Polyacrylic acid is a homopolymer composed of acrylic acid. The weight average molecular weight of the polyacrylic acid is not particularly limited, but is preferably 10,000 to 2,000,000, more preferably 25,000 to 1,800,000, and even more preferably 50,000 to 1,500,000.

Here, when a conventional polymer compound such as polyamideimide is used as the negative electrode binder, the cycle characteristics of the electrical storage device tend to decrease as the weight average molecular weight of the polymer compound decreases. On the other hand, when the polymer compound of the present embodiment is used as a negative electrode binder, the cycle characteristics of the electrical storage device are maintained even if the weight average molecular weight of the polyacrylic acid constituting the polymer compound decreases. Therefore, as the polyacrylic acid (A), a low molecular weight polyacrylic acid having a molecular weight of, for example, 250,000 or less or 100,000 or less is preferably used.

The polyfunctional amine is a compound having a structure represented by the following general formula (1).

[Chemical Formula 8]

In the general formula (1), Y is a linear alkyl group having 1 to 4 carbon atoms, a phenylene group, or an oxygen atom. The bonding position of Y in each benzene ring may be any of ortho, meta and para positions relative to the amino group.

When Y is a linear alkyl group or a phenylene group, a substituent may be bonded to the carbon atom constituting the structure. Examples of the substituent bonded to the carbon atom constituting the linear alkyl group include a methyl group, an ethyl group, a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a methoxy group, an ethoxy group and an oxo group. These substituents may be bonded to only one type, or two or more types may be bonded. The number of substituents bonded to one carbon atom may be one or two. The substituent bonded to the carbon atom constituting the linear alkyl group and the phenylene group may be a substituent containing an amino group or an amino group, and in this case, a polyfunctional amine having three or more amino groups.

In the general formula (1), R1 and R2 each independently represent a single or plural hydrogen atoms, a methyl group, an ethyl group, a trifluoromethyl group, or a methoxy group. In the case where R 1 is a methyl group, an ethyl group, a trifluoromethyl group or a methoxy group, the bonding position of R 1 may be any of ortho, meta and para positions relative to the amino group. The same is true for R2.

(B) Specific examples of the polyfunctional amine will be described.

Examples of polyfunctional amines in which Y is a linear alkyl group include 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'- 4,4'-diamino-3,3'-dimethyldiphenylmethane, 1,1-bis (4-aminophenyl) cyclohexane, 9,9- Fluorene, 2,2'-bis (4-aminophenyl) hexafluoropropane, 4,4'-diaminobenzophenone, 4,4'-methylenebis Nilin can be called. Examples of polyfunctional amines in which Y is a phenylene group include, for example, 1,3,5-tris (4-aminophenyl) benzene. As the polyfunctional amine in which Y is an oxygen atom, for example, 4,4'-diaminodiphenyl ether can be mentioned. 1,3,5-tris (4-aminophenyl) benzene, and para-rosaniline are trifunctional amines having three amino groups. Only one of the polyfunctional amines may be used, or two or more of them may be used in combination.

The mixing ratio of the polyacrylic acid (A) and the polyfunctional amine (B) when they are condensed is set according to the number of amino groups of the polyfunctional amine (B). That is, the compounding ratio is set such that the number of carboxyl groups in the polyacrylic acid (A) is larger than the number of amino groups in the polyfunctional amine (B). In other words, the compounding ratio is set such that the carboxyl group in the polyacrylic acid (A) is at least 1 equivalent based on one equivalent of the amino group in the polyfunctional amine (B). (Carboxyl group / amino group ratio) of the number of carboxyl groups of the polyacrylic acid (A) and the number of amino groups of the polyfunctional amine (B) is preferably in the range of 1.5 / 1 to 15/1, 1 < / RTI >

The polymer compound of the present embodiment is obtained by a mixing step of mixing (A) polyacrylic acid and (B) a polyfunctional amine in a solvent, and a heating step of heating the intermediate composition obtained in the mixing step.

The mixing step is a step of obtaining a liquid intermediate composition obtained by mixing (A) polyacrylic acid, (B) a polyfunctional amine and a solvent. As the solvent used in the mixing process, a solvent in which (A) the polyacrylic acid and (B) the polyfunctional amine are dissolved can be appropriately selected and used. Particularly, from the viewpoint of improving the solubility, it is preferable to use a non-aqueous solvent such as N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, dimethylsulfoxide, propylene carbonate,? -Butyrolactone, ethanol and propanol Do.

The heating step is a step of heating the intermediate composition to condense the polyacrylic acid (A) and the polyfunctional amine (B) contained in the intermediate composition. The heating temperature in the heating step is preferably in the range of 150 to 230 ° C, more preferably 180 to 200 ° C, from the viewpoint of promoting the formation of the crosslinked structure, that is, from the viewpoint of efficient formation of the amide bond portion and the imide bond portion More preferable. The heating temperature in the heating step is preferably in the range of 180 to 230 캜 from the viewpoint of forming an acid anhydride structure described later. When the heating temperature is increased, the characteristics (cycle characteristics) of a power storage device such as a secondary battery are enhanced when the polymer compound of the present embodiment is used as a negative electrode binder.

A catalyst may be added to the intermediate composition in order to advance the condensation reaction to form the amide bond and the imide bond or to increase the reaction rate of the condensation reaction. Examples of the catalyst include, for example, 1-methylimidazole, 2-methylimidazole, N, N'-dicyclohexylcarbodiimide, N, N'-carbonyldiimidazole, Ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride, diphenylphosphoric acid azide, diphenylphosphoric acid diiodide, diphenylphosphoric acid diiodide, diisopropylcarbodiimide, 1- [3- (dimethylamino) A dehydration condensation catalyst such as a BOP reagent can be effectively used. When these catalysts are added, the amide bond and the imide bond can be formed at a lower temperature, so that the production efficiency of the polymer compound is enhanced.

The intermediate composition provided in the heating process is preferably an intermediate composition that has undergone preheating treatment. The temperature of the preheating treatment is preferably in the range of 40 to 140 占 폚, and more preferably in the range of 60 to 130 占 폚. By the preliminary heating treatment, the polyacrylic acid (A) and the polyfunctional amine (B) contained in the intermediate composition are associated with each other to form a state in which the condensation reaction between the carboxyl group and the amino group proceeds. As a result, the condensation reaction proceeds efficiently in the heating process. The condensation reaction between the carboxyl group and the amino group proceeds partially by the preliminary heating treatment, and an amide bond portion or an imide bond portion may be formed.

When the intermediate composition subjected to the preheating treatment is used, the heating step is preferably carried out in a state in which the solvent contained in the intermediate composition is removed. In this case, the condensation reaction of the polyacrylic acid (A) and the polyfunctional amine (B) is likely to proceed.

By the heating step, a polymer compound in which (A) polyacrylic acid and (B) polyfunctional amine are condensed is obtained. (A) at least one of an amide bond and an imide bond is formed between the carboxyl group of the polyacrylic acid and the amino group of the polyfunctional amine (B), and (A) the polyacrylic acid has a cross-linked structure I think. In short, the polymer compound has a cross-linking structure connecting carboxylic acid side chains between a chain-like structure formed of polyacrylic acid and a chain-like structure in the chain-like structure. The crosslinking structure is at least one crosslinking structure selected from the following general formulas (2) to (4).

[Chemical Formula 9]

In the general formulas (2) to (4), PAA represents a chain-like structure composed of polyacrylic acid. X is a structure represented by the following general formula (5). In the general formulas (3) to (4) having an imide structure, the two carbonyl groups constituting one imide structure may be a carbonyl group bonded to a different chain structure or a carbonyl group bonded to the same chain structure It may be. For example, when the two carbonyl groups constituting the imide structure are carbonyl groups bonded to adjacent carbons in the same chain-like structure, a maleimide structure is formed as an imide structure.

[Chemical formula 10]

In the general formula (5), Y is a linear alkyl group having 1 to 4 carbon atoms, a phenylene group, or an oxygen atom. The bonding position of Y in each benzene ring may be any of ortho, meta and para positions relative to the amino group. Y in the general formula (5) has a structure according to Y in the general formula (1).

In the general formula (5), R1 and R2 each independently represent a single or plural hydrogen atoms, a methyl group, an ethyl group, a trifluoromethyl group, or a methoxy group. In the case where R 1 is a methyl group, a trifluoromethyl group or a methoxy group, the bonding position of R 1 may be any of ortho, meta and para positions relative to the amino group. The same is true for R2. R 1 and R 2 in the general formula (5) have a structure based on R 1 and R 2 in the general formula (1).

The polymer compound preferably has both an amide bond portion and an imide bond portion in its cross-linked structure. In short, it is preferable that at least a crosslinked structure of the general formula (2) and the general formula (4) or a crosslinked structure of at least the general formula (3) is used as the crosslinked structure.

The polymer compound preferably has an acid anhydride structure (CO-O-CO) formed by dehydration condensation of two carboxyl groups in the molecular structure. The acid anhydride structure may be a structure formed in the same chain-like structure (PAA) or a structure formed between different chain-like structures (PAA). That is, the two carbonyl carbons contained in the acid anhydride structure may be bonded to the same chain-like structure (PAA) or may be bonded to another chain-like structure (PAA), respectively.

The polymer compound of the present embodiment may be a polymer compound having a second crosslinking structure.

For example, a polymer compound having a second crosslinking structure may be a polymer compound obtained by condensing (A) a polyacrylic acid, (B) a polyfunctional amine represented by the general formula (1) and (C) other polyfunctional amine do. In this case, in addition to the crosslinked structure derived from the polyfunctional amine represented by the general formula (1), a polymer compound having a second crosslinked structure derived from other polyfunctional amine is obtained. By adding the second crosslinking structure, physical properties such as strength and flexibility of the polymer compound can be adjusted.

(C) Examples of other polyfunctional amines include 1,4-diaminobutane, 1,6-diaminohexane, 1,8-diaminooctane, 2-aminoaniline (1,2- (1,3-phenylene diamine), 4-aminoaniline (1,4-phenylenediamine), 2,4-diaminopyridine, 2,5-diaminopyridine, 2,6- Aminopyridine, and 1,3-diiminoisoindoline.

(C) other polyfunctional amine is preferably 1 part by mass or less based on 10 parts by mass of the polyfunctional amine (B) represented by the general formula (1). By setting the ratio to the above range, the physical properties such as the strength and flexibility of the polymer compound are greatly changed and can be suppressed from being not suitable for the negative electrode binder.

The polymer compound having a second crosslinking structure may be a polymer compound obtained by condensing (A) a polyacrylic acid, (B) a polyfunctional amine represented by the general formula (1) and (D) a polyfunctional carboxylic acid. In this case, in addition to the crosslinked structure derived from the polyfunctional amine represented by the general formula (1), a polymer compound having a second crosslinked structure derived from both the polyfunctional amine and the polyfunctional carboxylic acid represented by the general formula (1) . This second crosslinked structure is obtained by bonding two or more (B) polyfunctional amines represented by the general formula (1) and at least one (D) polyfunctional carboxylic acid by amide bond or imide bond, The structural part derived from the polyfunctional amine represented by the general formula (1) and the structural part derived from the polyfunctional carboxylic acid (D) are alternately arranged and the structural part derived from the polyfunctional carboxylic acid represented by the general formula (1) (A) is a crosslinked structure bonded to polyacrylic acid in a structural part derived from a polyfunctional amine. By adding the second crosslinking structure, physical properties such as strength and flexibility of the polymer compound can be adjusted.

The polyfunctional carboxylic acid (D) may be any compound having two or more carboxyl groups. Examples of the polyfunctional carboxylic acid (D) include oxalic acid, 1,2,3-propane, tricarboxylic acid, 1,2,3,4-butanetetracarboxylic acid, diglycolic acid, phthalic acid, Naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, 2,2'-biphenyl dicarboxylic acid, 3-naphthalene dicarboxylic acid, 3-naphthalene dicarboxylic acid, , 3'-biphenyldicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,2,4 -Cyclohexanetricarboxylic acid, 1,3,5-cyclohexanetricarboxylic acid, 1,2,4,5-cyclohexanetetracarboxylic acid, 1,2,3,4,5,6-cyclohexane Hexanecarboxylic acid, 1,3-adamantanedicarboxylic acid, 1,2-cyclopentanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,1,3-cyclopentanetricarboxylic acid Acid, 1,2,4-cyclopentanetricarboxylic acid, 1,3,4-cyclopentanetricarboxylic acid, 2,3,4,5-tetrahydrofuranetetracarboxylic acid, Chloride [2.2] loam-7-ene can be cited 2,3,5,6-tetracarboxylic acid dianhydride, 3,4,9,10-perylene tetracarboxylic acid dianhydride.

The mixing ratio of the polyfunctional carboxylic acid (D) to the polyfunctional carboxylic acid (B) is preferably such that the ratio of the number of amino groups of the polyfunctional amine (B) to the number of carboxyl groups of the polyfunctional carboxylic acid (D) / Number of carboxyl groups) is preferably in the range of 7 to 25, and more preferably in the range of 5 to 15.

The polymer compound of the present embodiment has a second crosslinked structure derived from other polyfunctional amine as the second crosslinked structure and a second crosslinked structure derived from both polyfunctional amine and polyfunctional carboxylic acid represented by formula (1) Or may be a polymer compound having both.

The polymer compound of the present embodiment may be a polymer compound having a structure in which monoamine is bonded. That is, it may be a polymer compound in which (A) polyacrylic acid and (B) a polyfunctional amine represented by the general formula (1) and (E) monoamine are condensed. The monoamine binds to a carboxyl group which is not bonded to a polyfunctional amine in polyacrylic acid to form a non-crosslinked structure.

(E) monoamines include, for example, aniline, aminophenol, morpholine, and 3-aminopyridine. The blending ratio of the (E) monoamine is preferably 1 part by mass or less based on 10 parts by mass of the polyfunctional amine (B) represented by the general formula (1). By setting the ratio to the above range, the physical properties such as the strength and flexibility of the polymer compound are greatly changed and can be suppressed from being not suitable for the negative electrode binder.

Next, an example of a method for producing a negative electrode using the polymer compound of the present embodiment as a negative electrode binder will be described.

First, a slurry is prepared by mixing a negative electrode active material, a negative electrode binder and a solvent. At this time, other components such as a conductive additive may be further added as necessary.

As the negative electrode active material, a known material used as a negative electrode active material of a power storage device such as a secondary battery, for example, a carbon-based material, an alloyable element with lithium, and a compound having an alloyable element with lithium can be used.

As the carbon-based material, for example, a carbon-based material capable of intercalating and deintercalating lithium can be used. Specific examples of the carbon-based material include non-graphitizable carbon, natural graphite, artificial graphite, cokes, Graphite, glassy carbon, sintered organic polymer compound, carbon fiber, activated carbon, and carbon black.

As the element which can be alloyed with lithium, for example, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Ti, Ag, Zn, Cd, , Sn, Pb, Sb and Bi. Of these, Si is particularly preferable.

Examples of the compound having an element capable of alloying with lithium include Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Ti, Ag, Zn, Cd, Si, Ge, Sn, Pb, Sb and Bi. Among them, a silicon-based material which is a compound having Si is particularly preferable.

As the silicon based material, for example, SiB ₄ , SiB ₆ , Mg ₂ Si, Ni ₂ Si, TiSi ₂ , MoSi ₂ , CoSi ₂ , NiSi ₂ , CaSi ₂ , CrSi ₂ , Cu ₅ Si, FeSi ₂ , MnSi ₂ , NbSi ₂ , TaSi ₂ , VSi ₂ , WSi ₂ , ZnSi ₂ , SiC, Si ₃ N ₄ , Si ₂ N ₂ O, SiO _V (0 <V ≤ 2), SnSiO ₃ and LiSiO. Of these, SiO 2 _V (0 &lt; V 2) is particularly preferred.

As a silicon-based material, a silicon material obtained by decalcification reaction from CaSi ₂ disclosed in International Publication No. 2014/080608 can also be used. The silicon material may be a silicon obtained by treating a layered polysilane obtained by treating CaSi ₂ with an acid (for example, hydrochloric acid or hydrogen fluoride) in a decalcification (for example, a heat treatment at 300 to 1000 ° C) Material. As the negative electrode active material, one type of material may be used alone, or a plurality of materials may be used together. The polymer compound of the present embodiment is particularly preferably used in combination with a silicon-based material which is a negative electrode active material having a high degree of expansion and shrinkage during charging and discharging.

As the negative electrode active material, only one of the above materials may be used, or two or more of them may be used in combination.

As the negative electrode binder to be mixed with the slurry, the above-mentioned intermediate composition is used.

As the negative electrode binder, other negative electrode binders may be used in combination. Examples of other negative electrode binders include polyvinylidene fluoride, polytetrafluoroethylene, styrene-butadiene rubber, polyimide, polyamideimide, carboxymethylcellulose, polyvinyl chloride, methacrylic resin, polyacrylonitrile, Polyphenylene oxide, polyethylene oxide, polyethylene, polypropylene, polyacrylic acid and phenol resin. Only one of these other negative electrode binders may be used, or two or more of them may be used in combination. When other negative electrode binders are used in combination, the solid content of the intermediate composition is preferably 1% by mass or more, more preferably 10% by mass or more, based on the total solid content of the negative electrode binder.

The mixing ratio (negative electrode active material: binder for negative electrode) in the mass ratio of the negative electrode active material and negative electrode binder can be appropriately set in accordance with the kind of the negative electrode active material and the negative electrode binder. The blending ratio is preferably in the range of, for example, 5: 3 to 99: 1, more preferably 3: 1 to 97: 3, even more preferably 16: 3 to 95: 5 Do. When the negative electrode active material is the silicon material disclosed in International Publication No. 2014/080608, the mixing ratio (negative electrode active material: negative electrode binder) in the mass ratio of the negative electrode active material and negative electrode binder is 3: 1 to 7.5: 1 , More preferably in the range of 4: 1 to 5: 1.

As the solvent, a known solvent used at the time of manufacturing an electrode of a power storage device such as a secondary battery can be appropriately used depending on the kind of the negative electrode active material and the negative electrode binder. Specific examples of the solvent include N-methyl-2-pyrrolidone, methanol, and methyl isobutyl ketone.

As the conductive auxiliary agent, a known conductive auxiliary agent used for a negative electrode of a power storage device such as a secondary battery can be used. Specific examples of the conductive auxiliary agent include acetylene black, carbon nanotubes, and ketjen black. Of these conductive auxiliary agents, only one kind may be used, or two or more kinds may be used in combination.

For example, when acetylene black and carbon nanotubes or Ketjenblack are used in combination, the characteristics (cycle characteristics) of the electrical storage device are improved as compared with the case where acetylene black alone is used. When the acetylene black and the carbon nanotube are used in combination, the mixing ratio (carbon nanotube / acetylene black) in the mass ratio of these conductive auxiliary agents is preferably in the range of 0.2 to 4.0, more preferably in the range of 0.2 to 1.0 More preferable. When acetylene black and ketjen black are used in combination, the mixing ratio (Ketjenblack / acetylene black) in the mass ratio of these conductive auxiliary agents is preferably in the range of 0.2 to 1.0.

When acetylene black is used as the conductive auxiliary agent, acetylene black preferably has a 50% particle diameter (D50) in the range of 0.35 to 0.75 占 퐉, a 10% particle diameter (D10) in the range of 0.18 to 0.25 占 퐉, It is more preferable that the particle diameter (D90) is in the range of 1.6 to 3.5 mu m. By setting to the above range, the characteristics (cycle characteristics) of the electrical storage device by acetylene black can be effectively improved. The 50% particle diameter means the secondary particle diameter of acetylene black at an integrated value of 50% in the particle size distribution obtained by the laser diffraction / scattering method. The same is true for 10% particle size and 90% particle size.

The mixing ratio of acetylene black is preferably in the range of 0.5 to 1.5 parts by mass based on 1 part by mass of the negative electrode binder. By setting the above range, it is possible to effectively improve the characteristics (initial efficiency and cycle characteristics) of the power storage device by acetylene black.

When the conductive auxiliary agent is contained in the slurry, it is preferable to include a dispersant together with the conductive auxiliary agent. Specific examples of the dispersing agent include polyvinyl pyrrolidone, polyvinyl alcohol, polyvinyl butyral, and triazine compounds. Of these dispersants, only one type may be used, or two or more types may be used in combination.

Subsequently, the slurry is applied to the current collector to form a negative electrode active material layer made of slurry on the surface of the current collector. Thereafter, the solvent (the solvent of the slurry and the solvent contained in the intermediate composition) contained in the negative electrode active material layer is removed, and the negative electrode active material layer is dried and cured by heat treatment. By this heat treatment, the polyacrylic acid (A) and the polyfunctional amine (B) contained in the intermediate composition are condensed to form the polymer compound of the present embodiment in the negative electrode active material layer. The heat treatment may be carried out while the solvent is contained in the negative electrode active material layer, but the negative electrode active material layer is more preferably dried.

Specific examples of the drying treatment and the heat treatment include a method of heating by using a heat source such as hot air, infrared ray, microwave, or high frequency under atmospheric pressure or reduced pressure. In the heat treatment, it is preferable to heat from the current collector rather than from the negative electrode active material layer. The drying treatment is preferably performed slowly at a low temperature rather than at a high temperature, and it is preferable that the heating treatment is performed at a high temperature faster than a slow heating at a low temperature. By heating in this way, the characteristics (initial efficiency and cycle characteristics) of the power storage device can be increased.

As the current collector, a known metallic material used as a current collector for a negative electrode of a power storage device such as a secondary battery can be used. Examples of the metal material usable in the current collector include metals such as silver, copper, gold, aluminum, magnesium, tungsten, cobalt, zinc, nickel, iron, platinum, tin, indium, titanium, ruthenium, tantalum, molybdenum, .

The negative electrode using the polymer compound of the present embodiment as a negative electrode binder can be effectively used in a non-aqueous storage device having a non-aqueous electrolyte as an electrolyte. Examples of the electrical storage device include a secondary battery, an electric double layer capacitor, and a lithium ion capacitor. Such a power storage device is useful as a non-aqueous secondary battery for driving electric motors and motors of hybrid vehicles, and as a non-aqueous secondary battery for use in personal computers, portable communication devices, home appliances, office equipment, industrial devices and the like.

Next, effects of the present embodiment will be described.

(1) The polymer compound of the present embodiment is a compound obtained by condensing polyacrylic acid with a polyfunctional amine represented by the general formula (1). The polymer compound of the present embodiment has a crosslinked structure connecting carboxylic acid side chains between a chained structure formed of polyacrylic acid and a chained structure or a chained structure, , And at least one crosslinking structure selected from the above general formulas (2) to (4). The polymer compound of the present embodiment is a compound obtained by heat-treating an intermediate composition containing a polyacrylic acid, a polyfunctional amine represented by the general formula (1), and a non-aqueous solvent and forming a liquid phase.

The polymer compound of the present embodiment is useful as a negative electrode binder of a power storage device. By using the polymer compound of the present embodiment as a negative electrode binder, the characteristics (initial efficiency and cycle characteristics) of the electrical storage device can be increased.

The polymer compound of the present embodiment as a negative electrode binder has a property that cycle characteristics of a power storage device are easily maintained even when the weight average molecular weight of a polyacrylic acid chain structure is reduced. Therefore, even when the short-chain structure portion is made of a short-molecular-weight polymer compound, it can effectively function as a negative electrode binder. When a polymer compound having a low molecular weight is used as the negative electrode binder, the solid content ratio of the slurry can be set to a large value since the slurry can be prepared with a smaller amount of solvent. By increasing the solid content ratio of the slurry, the drying time for volatilizing the solvent from the negative electrode active material layer at the time of manufacturing the negative electrode is shortened, and the productivity of the negative electrode is improved. Therefore, when the polymer compound of the present embodiment is used as the negative electrode binder, it is easy to improve the productivity of the negative electrode.

(2) In the partial structure of the crosslinked structure represented by the general formula (5), Y is a linear alkyl group having 1 to 4 carbon atoms, a phenylene group, or an oxygen atom.

According to the above configuration, the stretchability of the polymer compound is improved because the polymer has a partial structure capable of moving within the crosslinked structure. As a result, the negative electrode binder using the polymer compound of the present embodiment can easily follow changes in volume due to expansion and contraction accompanying occlusion and release of lithium and the like. As a result, the characteristics of the electrical storage device are enhanced.

(3) The polymer compound of the present embodiment has a moiety in which a carboxyl group of polyacrylic acid and an amino group of a polyfunctional amine are bonded by an amide bond and a moiety bonded by an imide bond. The polymer compound of the present embodiment has at least a crosslinked structure of the formula (2) and the formula (4), or at least a crosslinked structure of the formula (3) as the crosslinked structure.

According to the above configuration, in the state of the negative electrode formed by mixing the polymer compound with the negative electrode active material, the strength of the electrode structure is increased. Thereby, the electrode structure can be easily maintained with respect to the volume change due to the expansion and contraction accompanying the occlusion and discharge of lithium and the like. As a result, the characteristics of the electrical storage device can be surely enhanced.

Further, according to the above configuration, the solubility of the polymer compound with respect to the organic matter such as the non-aqueous electrolyte deteriorates. Therefore, the effect of inhibiting the elution of the polymer compound into the non-aqueous electrolyte during the electrochemical reaction is also obtained.

(4) The blending ratio of polyacrylic acid and polyfunctional amine (polyfunctional amine represented by general formula (1)) is not more than 15 equivalents of the carboxyl group in polyacrylic acid with respect to one amino group in polyfunctional amine.

When the equivalence of the carboxyl group to the amino group is lowered, the imido bond is likely to be formed as a condensation unit between the carboxyl group and the amino group. Therefore, according to the above configuration, the imaged joint portion can be efficiently formed. As a result, the effect of (3) can be obtained more reliably.

(5) The blending ratio of polyacrylic acid and polyfunctional amine (polyfunctional amine represented by general formula (1)) is 1.5 equivalents or more of the carboxyl group in polyacrylic acid with respect to one amino group in polyfunctional amine. When the equivalence of the carboxyl group to the amino group is increased, more crosslinked structure is formed, so that the resin strength of the polymer compound is increased. Therefore, according to the above-described structure, the resin strength due to the formation of the crosslinked structure can be more reliably improved.

In addition, when the equivalence of the carboxyl group to the amino group is increased, the carboxyl group not involved in the crosslinking structure is increased, so that the acid anhydride structure is easily formed.

Example

Hereinafter, an embodiment in which the above-described embodiment is further specified will be described.

<Test 1>

The intermediate compositions of the other Examples 1 to 3 were prepared with polyfunctional amines. Hereinafter, polyacrylic acid is denoted by "PAA", N-methyl-2-pyrrolidone is denoted by "NMP", and polyamideimide is denoted by "PAI".

(Example 1: PAA + 4,4'-diaminodiphenylmethane)

PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a 10 mass% PAA / NMP solution. 7 ml of this PAA / NMP solution (9.5 mmol in terms of monomer of PAA) was collected in a flask under a nitrogen atmosphere. Separately, 0.1 g (0.5 mmol) of 4,4'-diaminodiphenylmethane was dissolved in 0.4 ml of NMP to prepare an amine / NMP solution. While stirring the PAA / NMP solution in the flask, the total amount of the amine / NMP solution was dropped into the PAA / NMP solution, and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 1 was obtained in the form of an NMP solution by heat treatment (preheating treatment) at 130 占 폚 for 3 hours using a Dean-Stark apparatus.

(Example 2: PAA + 4,4'-diaminodiphenyl ether)

PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a PAA / NMP solution of 10 mass%, and 7 ml of this PAA / NMP solution was collected in a flask under a nitrogen atmosphere. Separately, 0.1 g (0.5 mmol) of 4,4'-diaminodiphenyl ether was dissolved in 0.4 ml of NMP to prepare an amine / NMP solution. While stirring the PAA / NMP solution in the flask, the total amount of the amine / NMP solution was dropped into the PAA / NMP solution, and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 2 was obtained in the form of an NMP solution by a heat treatment (preheating treatment) at 130 占 폚 for 3 hours using a Dean-Stark apparatus.

As a reference example, a polymer compound having PAA and a polyfunctional amine that does not satisfy the above general formula (1) was condensed was synthesized.

(Reference Example 1: PAA + 1, 6-diaminohexane)

PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a PAA / NMP solution of 10 mass%, and 7 ml of this PAA / NMP solution was collected in a flask under a nitrogen atmosphere. Separately, 65 占 (0.5 mmol) of 1,6-diaminohexane was dissolved in 0.4 ml of NMP to prepare an amine / NMP solution. While stirring the PAA / NMP solution in the flask, the total amount of the amine / NMP solution was dropped into the PAA / NMP solution, and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Reference Example 1 was obtained in the form of an NMP suspension by heating (preheating treatment) at 130 캜 for 3 hours using a Dean-Stark apparatus.

(Reference Example 2: PAA + 2,2'-oxybis (ethylamine))

PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a PAA / NMP solution of 10 mass%, and 7 ml of this PAA / NMP solution was collected in a flask under a nitrogen atmosphere. Separately, 53 μl (0.5 mmol) of 2,2'-oxybis (ethylamine) was dissolved in 0.4 ml of NMP to prepare an amine / NMP solution. While stirring the PAA / NMP solution in the flask, the total amount of the amine / NMP solution was dropped into the PAA / NMP solution, and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Reference Example 2 was obtained in the form of an NMP suspension by heating treatment (preheating treatment) at 130 占 폚 for 3 hours using a Dean-Stark apparatus.

(Reference Example 3: PAA + 2-methyl-5-aminoaniline)

PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a PAA / NMP solution of 10 mass%, and 7 ml of this PAA / NMP solution was collected in a flask under a nitrogen atmosphere. Separately, 0.061 g (0.5 mmol) of 2-methyl-5-aminoaniline was dissolved in 0.4 ml of NMP to prepare an amine / NMP solution. While stirring the PAA / NMP solution in the flask, the total amount of the amine / NMP solution was dropped into the PAA / NMP solution, and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Reference Example 3 was obtained in the form of an NMP solution by heating (preheating treatment) at 130 캜 for 3 hours using a Dean-Stark apparatus.

(Preparation of electrode sheet)

Next, using the intermediate composition of Examples 1 and 2, an electrode sheet was produced using the polymer compound obtained from each intermediate composition as a negative electrode binder. The obtained electrode sheet was used to fabricate a lithium ion secondary battery, and the battery characteristics of the lithium ion secondary battery were evaluated.

85 parts by mass of SiO 2, 5 parts by mass of acetylene black and 10 parts by mass of an NMP solution of the intermediate composition of Examples 1 and 2 were mixed and NMP was added to this mixture to prepare a slurry. On the surface of an electrolytic copper foil (collector) having a thickness of 30 占 퐉, a slurry was applied in a film form using a doctor blade method. Then, NMP in the slurry was volatilized and removed to form a negative electrode active material layer on the electrolytic copper foil. Subsequently, the electrolytic copper foil and the negative electrode active material layer were compressed using a roll press machine so that the thickness of the negative electrode active material layer was 20 占 퐉, thereby bonding the electrolytic copper foil and the negative electrode active material layer tightly.

Thereafter, the negative electrode active material layer in which NMP was removed and dried was subjected to a heat treatment in vacuum (under reduced pressure) at 160 DEG C for 3 hours to condense the intermediate composition contained in the negative electrode active material layer, The active material layer was cured by heating. Thus, an electrode sheet containing a polymer compound having a crosslinked structure as a negative electrode binder was obtained.

An electrode sheet using PAA, PAI (a polymer compound having an amide bond portion and an imide bond portion in a molecular structure) as a negative electrode binder was prepared in the same manner as a comparative sample. Also, the electrode sheets were prepared in the same manner using the intermediate compositions of Reference Examples 1 to 3.

(Preparation of Lithium Ion Secondary Battery)

A separator was disposed between a negative electrode (evaluation electrode) formed by cutting the electrode sheet into a circular shape with a diameter of 11 mm and a positive electrode formed by cutting a metallic lithium foil having a thickness of 500 mu m into a circle having a diameter of 13 mm, . A non-aqueous electrolyte was charged into the battery case while accommodating the electrode body battery, and the battery case was closed to obtain a lithium ion secondary battery. As the separator, a glass filter manufactured by Phahysters Celanese and celgard2400 manufactured by Celgard Corporation were used. As the non-aqueous electrolyte, a nonaqueous electrolyte in which lithium hexafluorophosphate was dissolved to a concentration of 1 M was used in a mixed solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1.

(Evaluation of Battery Characteristics)

The obtained lithium ion battery was discharged at a direct current of 0.2 mA until the voltage applied to the positive electrode of the negative electrode reached 0.01 V. After 10 minutes from the end of the discharge, Was charged until the voltage with respect to the positive electrode of the battery was 1.0 V. The discharging capacity at this time was taken as the initial discharging capacity and the charging capacity was taken as the initial charging capacity. Then, the initial efficiency was calculated based on the following formula. The results are shown in Table 1.

Initial efficiency (%) = (initial charge capacity / initial discharge capacity) x 100

Further, the discharging and charging were performed as one cycle, and charging and discharging in a prescribed cycle were carried out, and the cycle characteristics were calculated based on the following formula. The results are shown in Table 1.

Cycle characteristic (%) = (charge capacity after prescribed cycle / initial charge capacity) x 100

As shown in Table 1, in Test Examples 1 and 2 using the negative electrode binder of Examples 1 and 2, the initial efficiency and the cycle characteristics together exhibited high values. On the other hand, in Test Examples 3 and 4 using PAI and PAA as negative electrode binders and Test Examples 5 to 7 using Referential Examples 1 to 3, it was found that one or both of initial efficiency and cycle characteristics showed low values lost. Particularly, in Test Example 7, although polyfunctional amine common to Examples was used in that it had an aromatic ring as a constituent element of the negative electrode binder, the initial discharge capacity, initial charge capacity, and initial efficiency were low. In the negative electrode binder of Reference Example 3, the connecting portion corresponding to the Y portion of the general formula (1) does not exist, and it is considered that the negative electrode binder does not follow the volume change accompanied by occlusion and release of lithium.

From these results, it was confirmed that the polymer compound obtained by condensing polyacrylic acid and a polyfunctional amine having a specific molecular structure was useful as a negative electrode binder of a power storage device such as a secondary battery.

<Test 2>

Next, with respect to the intermediate composition of Example 1, the change in the battery characteristics when the carboxyl group / amino group ratio was varied by evaluating the blending ratio of PAA and the polyfunctional amine was evaluated.

(Examples 1-1 to 1-4: PAA + 4,4'-diaminodiphenylmethane)

With respect to the intermediate composition of Example 1, the amount of 4,4'-diaminodiphenylmethane was varied to obtain an intermediate composition of Examples 1-1 to 1-4 having different carboxyl group / amino group ratios. The ratio of carboxyl group / amino group in each example is as shown in Table 2. Example 1-1 is the same intermediate composition as in Example 1, and its carboxyl / amino group ratio is "9.5 / 1". Examples 1-2 to 1-4 were prepared in the same manner as in Example 1 except that the amount of 4,4'-diaminodiphenylmethane was changed.

(Evaluation of Battery Characteristics)

Using the intermediate compositions of Examples 1-1 to 1-4, an electrode sheet using a polymer compound obtained from the intermediate composition as a negative electrode binder was produced. The obtained electrode sheet was used to fabricate a lithium ion secondary battery, and the battery characteristics of the lithium ion secondary battery were evaluated. The results are shown in Table 2. The method of manufacturing the electrode sheet and the lithium ion secondary battery, and the method of evaluating the battery characteristics of the lithium ion secondary battery are the same as those described above.

As shown in Table 2, it was confirmed that the cycle characteristics of the secondary battery were improved as the ratio of the carboxyl group to the amino group became larger.

<Test 3>

Next, with respect to the intermediate composition of Example 1, the change in the battery characteristics when the conditions of the preheating treatment at the time of preparation of the intermediate composition were made different was evaluated.

(Example 1-1A: PAA + 4,4'-diaminodiphenylmethane)

PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a 10 mass% PAA / NMP solution. 7 ml of this PAA / NMP solution (9.5 mmol in terms of monomer of PAA) was collected in a flask under a nitrogen atmosphere. Separately, 0.1 g (0.5 mmol) of 4,4'-diaminodiphenylmethane was dissolved in 0.4 ml of NMP to prepare an amine / NMP solution. While stirring the PAA / NMP solution in the flask, the total amount of the amine / NMP solution was dropped into the PAA / NMP solution, and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 1-1A was obtained in the form of an NMP solution by heating treatment (preheating treatment) at 80 DEG C for 3 hours using a Dean-Stark apparatus.

(Example 1-1B: PAA + 4,4'-diaminodiphenylmethane)

PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a 10 mass% PAA / NMP solution. 7 ml of this PAA / NMP solution (9.5 mmol in terms of monomer of PAA) was collected in a flask under a nitrogen atmosphere. Separately, 0.1 g (0.5 mmol) of 4,4'-diaminodiphenylmethane was dissolved in 0.4 ml of NMP to prepare an amine / NMP solution. The intermediate composition of Example 1-1B was dissolved in an NMP solution (1 mL) by stirring the PAA / NMP solution in the flask while dropwise adding the total amount of the amine / NMP solution into the PAA / NMP solution and continuing stirring at room temperature .

(Battery evaluation)

Using the intermediate composition obtained in Examples 1-1A and 1-1B, an electrode sheet was prepared using the polymer compound obtained from the intermediate composition as a negative electrode binder. The obtained electrode sheet was used to fabricate a lithium ion secondary battery, and the battery characteristics of the lithium ion secondary battery were evaluated. The results are shown in Table 2. The electrode sheet, the method for manufacturing the lithium ion secondary battery, and the method for evaluating the battery characteristics of the lithium ion secondary battery are the same as those described above.

As shown in Table 3, also in Test Example 13 in which the preheating treatment was not performed at the time of preparation of the intermediate composition, the initial efficiency and cycle characteristics also showed high values. From the comparison of Test Example 13 and Test Examples 8 and 12, it was confirmed that the cycle characteristics of the secondary battery were further improved by performing the preheating treatment at the time of preparation of the intermediate composition and increasing the temperature during the preheating treatment I could.

<Test 4>

Next, the change in the battery characteristics when the conditions of the heat treatment of the negative electrode active material layer at the time of producing the electrode sheet were made different was evaluated.

(Preparation of electrode sheet)

85 parts by mass of SiO 2, 5 parts by mass of acetylene black, and 10 parts by mass of an NMP solution of the intermediate composition of Example 1-2 were mixed and NMP was added to the mixture to prepare a slurry. The surface of the electrolytic copper foil of 30 占 퐉 as the current collector was coated with a slurry in the form of a film using a doctor blade method. Then, NMP in the slurry was volatilized and removed to form a negative electrode active material layer on the electrolytic copper foil. Subsequently, the electrolytic copper foil and the negative electrode active material layer were compressed using a roll press machine so that the thickness of the negative electrode active material layer was 20 占 퐉, thereby bonding the electrolytic copper foil and the negative electrode active material layer tightly.

Subsequently, the negative active material layer in which the NMP was removed and dried was subjected to heat treatment in vacuum (under reduced pressure) with different temperatures and times as shown in Table 4, The composition was subjected to a condensation reaction, and the negative electrode active material layer was heated and cured. Thus, an electrode sheet containing a polymer compound having a crosslinked structure as a negative electrode binder was obtained.

(Evaluation of Battery Characteristics)

The obtained electrode sheet was used to fabricate a lithium ion secondary battery, and the battery characteristics of the lithium ion secondary battery were evaluated. The results are shown in Table 4. The manufacturing method of the lithium ion secondary battery and the method of evaluating the battery characteristics of the lithium ion secondary battery are the same as those described above.

As shown in Table 4, in Test Examples 15 and 16 in which the heat treatment was performed at 180 占 폚 and 200 占 폚, the cycle characteristics of the secondary battery were improved as compared with Test Example 9 in which the heat treatment was performed at 160 占 폚.

On the other hand, in the test example 17 in which the heat treatment was performed at 260 占 폚, the cycle characteristics of the secondary battery were lowered as compared with the test example 9 in which the heat treatment was performed at 160 占 폚. The reason for this is thought to be that decomposition occurred in the polymer compound having a crosslinked structure formed by the condensation reaction due to the excessively high temperature during the heat treatment. Also, in Test Example 14 in which the heat treatment was performed at 130 占 폚, the cycle characteristics of the secondary battery were lowered compared with Test Example 9 in which the heat treatment was performed at 160 占 폚. This is probably due to the fact that the polymer compound having a crosslinked structure is not sufficiently formed due to the excessively low temperature during the heat treatment.

From these results, it is considered that formation of a polymer compound having a crosslinked structure, which has undergone condensation reaction by heat treatment, contributes greatly to improvement of the cycle characteristics of the secondary battery. It is considered that the temperature of the heat treatment is preferably in the range of 150 to 230 占 폚.

<Test 5>

Next, the battery characteristics in the case of using the silicon material formed of the layered polysilane as the negative electrode active material were evaluated. In this test, the polymer compound obtained from the intermediate composition of Example 1 was used as a negative electrode binder.

(Fabrication of silicon material)

5 g of CaSi ₂ was added to 20 ml of concentrated hydrochloric acid containing 1% by mass of hydrogen fluoride in an ice bath at 0 ° C, and the mixture was stirred for 1 hour and then water was further added thereto, followed by stirring for 5 minutes. The reaction solution was filtered, and the resulting yellow powder was washed with water and ethanol, and dried under reduced pressure to obtain a layered polysilane. The obtained layered polysilane was heated to 500 캜 under an argon atmosphere to obtain a silicon material in which hydrogen was removed from the polysilane.

(Preparation of electrode sheet)

70 parts by mass of the silicone material, 15 parts by mass of natural graphite, 5 parts by mass of acetylene black and 10 parts by mass of an NMP solution of the intermediate composition of Example 1 were mixed and NMP was added to the mixture to prepare a slurry. The surface of the electrolytic copper foil of 30 占 퐉 as the current collector was coated with a slurry in the form of a film using a doctor blade method. Then, NMP in the slurry was volatilized and removed to form a negative electrode active material layer on the electrolytic copper foil. Subsequently, the electrolytic copper foil and the negative electrode active material layer were compressed using a roll press machine so that the thickness of the negative electrode active material layer was 20 占 퐉, thereby bonding the electrolytic copper foil and the negative electrode active material layer tightly.

Thereafter, the negative electrode active material layer in which NMP was removed and dried was subjected to a heat treatment in vacuum (under reduced pressure) at 180 DEG C for 2 hours to cause the intermediate composition contained in the negative electrode active material layer to undergo a condensation reaction, The active material layer was cured by heating. Thus, an electrode sheet containing a polymer compound having a crosslinked structure as a negative electrode binder was obtained. In place of the NMP solution of the examples, PAI and PAA were used to prepare the same electrode sheet.

(Evaluation of Battery Characteristics)

The obtained electrode sheet was used to fabricate a lithium ion secondary battery, and the battery characteristics of the lithium ion secondary battery were evaluated. The results are shown in Table 4. The manufacturing method of the lithium ion secondary battery and the method of evaluating the battery characteristics of the lithium ion secondary battery are the same as those described above.

As shown in Table 5, in Test Example 18 using Example 1 as the negative electrode binder, the initial efficiency and the cycle characteristics together exhibited high values. On the contrary, in Test Examples 19 and 20 in which PAI and PAA were used as the negative electrode binder, results showing that either or both of the initial efficiency and cycle characteristics were low was obtained. From this result, even when a silicon material formed of layered polysilane is used as the negative electrode active material, the polymer compound obtained by condensing polyacrylic acid and polyfunctional amine having a specific molecular structure can be used as a binder for a negative electrode of a power storage device such as a secondary battery .

<Test 6>

Next, the battery characteristics in the case of using a polymer compound obtained by condensing PAA and trifunctional amine as negative electrode binder were evaluated.

(Example 3: PAA + 1,3,5-tris (4-aminophenyl) benzene)

PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a 10 mass% PAA / NMP solution, and 2.33 ml (3.0 mmol in terms of monomer of PAA) of this PAA / NMP solution was collected in a flask under a nitrogen atmosphere. Separately, 0.105 g (0.3 mmol) of 1,3,5-tris (4-aminophenyl) benzene was dissolved in 0.4 ml of NMP to prepare an amine / NMP solution. While stirring the PAA / NMP solution in the flask, the total amount of the amine / NMP solution was dropped into the PAA / NMP solution, and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 3 was obtained in the form of an NMP solution by heating treatment (preheating treatment) at 130 占 폚 for 3 hours using a Dean-Stark apparatus.

(Evaluation of Battery Characteristics)

Using the intermediate composition of Example 3 as a negative electrode binder, an electrode sheet using the above-mentioned silicon material as an active material was produced by the same method as above. The obtained electrode sheet was used to fabricate a lithium ion secondary battery, and the battery characteristics of the lithium ion secondary battery were evaluated. The results are shown in Table 6. The method of producing the electrode sheet is the same as that of &lt; Test 5 &gt;. The manufacturing method of the lithium ion secondary battery and the method of evaluating the battery characteristics of the lithium ion secondary battery are the same as those described above.

As shown in Table 6, the initial efficiency and cycle characteristics in Test Example 21 using the polymer compound of Example 3 as the negative electrode binder were the same as the initial efficiency and cycle characteristics in Test Example 18 using the negative electrode binder Cycle characteristics. From these results, it was confirmed that the polymeric compound obtained by condensing PAA and trifunctional amine is equally useful as a negative electrode binder of a power storage device such as a secondary battery.

<Test 7>

Next, the battery characteristics in the case of using natural graphite as the negative electrode active material were evaluated. In this test, the polymer compound obtained from the intermediate composition of Example 1 was used as a negative electrode binder.

(Preparation of electrode sheet)

95 parts by mass of natural graphite (particle diameter 15 占 퐉) and 5 parts by mass of the NMP solution of the intermediate composition of Example 1 were mixed and NMP was added to this mixture to prepare a slurry. The surface of the electrolytic copper foil of 30 占 퐉 as the current collector was coated with a slurry in the form of a film using a doctor blade method. Then, NMP in the slurry was volatilized and removed to form a negative electrode active material layer on the electrolytic copper foil. Subsequently, the electrolytic copper foil and the negative electrode active material layer were compressed using a roll press machine so that the thickness of the negative electrode active material layer was 20 占 퐉, thereby bonding the electrolytic copper foil and the negative electrode active material layer tightly.

Thereafter, the negative electrode active material layer in which NMP was removed and dried was subjected to a heat treatment in vacuum (under reduced pressure) at 180 DEG C for 2 hours to cause the intermediate composition contained in the negative electrode active material layer to undergo a condensation reaction, The active material layer was cured by heating. Thus, an electrode sheet containing a polymer compound having a crosslinked structure as a negative electrode binder was obtained. Further, instead of the NMP solution of the examples, the same electrode sheet was prepared by using the PAA aqueous solution and the PAA NMP solution.

(Evaluation of Battery Characteristics)

The obtained electrode sheet was used to fabricate a lithium ion secondary battery, and the battery characteristics of the lithium ion secondary battery were evaluated. The results are shown in Table 7. The manufacturing method of the lithium ion secondary battery and the method of evaluating the battery characteristics of the lithium ion secondary battery are the same as those described above.

As shown in Table 7, in Test Example 22 using Example 1 as the negative electrode binder, results showing high initial efficiency were obtained as compared with Test Examples 23 and 24 using PAA. From these results, it was confirmed that even when natural graphite is used as the negative electrode active material, the polymer compound obtained by condensing polyacrylic acid and a polyfunctional amine having a specific molecular structure is useful as a negative electrode binder in a power storage device such as a secondary battery there was.

It is also known that the negative electrode using natural graphite as the negative electrode active material changes its volume with the occlusion and release of lithium. Therefore, it is considered that the effect of improving the cell characteristics in a polymer compound formed by condensing polyacrylic acid with a polyfunctional amine having a specific molecular structure is based on a stable change in volume accompanying lithium intercalation and deintercalation .

<Test 8>

Next, the battery characteristics were evaluated in the case where a polymer compound in which PAA and another polyfunctional amine having a structure satisfying the above-mentioned general formula (1) were condensed as a negative electrode binder.

(Example 4: PAA + 3,3'-diaminodiphenylmethane)

PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a 10 mass% PAA / NMP solution. 7 ml of this PAA / NMP solution (9.5 mmol in terms of monomer of PAA) was collected in a flask under a nitrogen atmosphere. Separately, 0.475 g (2.375 mmol) of 3,3'-diaminodiphenylmethane was dissolved in 0.4 ml of NMP to prepare an amine / NMP solution. While stirring the PAA / NMP solution in the flask, the total amount of the amine / NMP solution was dropped into the PAA / NMP solution, and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 4 was obtained in the form of an NMP solution by heat treatment (preheating treatment) at 130 占 폚 for 3 hours using a Dean-Stark apparatus.

(Example 5: PAA + 3,4'-diaminodiphenylmethane)

PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a 10 mass% PAA / NMP solution. 7 ml of this PAA / NMP solution (9.5 mmol in terms of monomer of PAA) was collected in a flask under a nitrogen atmosphere. Separately, 0.475 g (2.375 mmol) of 3,4'-diaminodiphenylmethane was dissolved in 0.4 ml of NMP to prepare an amine / NMP solution. While stirring the PAA / NMP solution in the flask, the total amount of the amine / NMP solution was dropped into the PAA / NMP solution, and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 5 was obtained in the form of an NMP solution by heat treatment (preheating treatment) at 130 占 폚 for 3 hours using a Dean-Stark apparatus.

(Example 6: PAA + 4,4'-ethylene dianiline)

PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a 10 mass% PAA / NMP solution. 7 ml of this PAA / NMP solution (9.5 mmol in terms of monomer of PAA) was collected in a flask under a nitrogen atmosphere. Separately, 0.51 g (2.375 mmol) of 4,4'-ethylenedianiline was dissolved in 0.4 ml of NMP to prepare an amine / NMP solution. While stirring the PAA / NMP solution in the flask, the total amount of the amine / NMP solution was dropped into the PAA / NMP solution, and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 6 was obtained in the form of an NMP solution by heating treatment (preheating treatment) at 130 占 폚 for 3 hours using a Dean-Stark apparatus.

(Example 7: PAA + 4,4'-diamino-3,3'-dimethyldiphenylmethane)

PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a 10 mass% PAA / NMP solution. 7 ml of this PAA / NMP solution (9.5 mmol in terms of monomer of PAA) was collected in a flask under a nitrogen atmosphere. Separately, 0.54 g (2.375 mmol) of 4,4'-diamino-3,3'-dimethyldiphenylmethane was dissolved in 0.4 ml of NMP to prepare an amine / NMP solution. While stirring the PAA / NMP solution in the flask, the total amount of the amine / NMP solution was dropped into the PAA / NMP solution, and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 7 was obtained in the form of an NMP solution by a heat treatment (preheating treatment) using a Dean-Stark apparatus at 130 캜 for 3 hours.

(Example 8: PAA + 2,2'-bis (4-aminophenyl) hexafluoropropane)

PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a 10 mass% PAA / NMP solution. 7 ml of this PAA / NMP solution (9.5 mmol in terms of monomer of PAA) was collected in a flask under a nitrogen atmosphere. Separately, 0.8 g (2.375 mmol) of 2,2'-bis (4-aminophenyl) hexafluoropropane was dissolved in 0.4 ml of NMP to prepare an amine / NMP solution. While stirring the PAA / NMP solution in the flask, the total amount of the amine / NMP solution was dropped into the PAA / NMP solution, and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 8 was obtained in the form of an NMP solution by heating treatment (preheating treatment) at 130 占 폚 for 3 hours using a Dean-Stark apparatus.

(Preparation of electrode sheet)

85 parts by mass of SiO 2, 5 parts by mass of acetylene black and 10 parts by mass of an NMP solution of the intermediate composition of Examples 4 to 8 were mixed and NMP was added to this mixture to prepare a slurry. On the surface of an electrolytic copper foil (collector) having a thickness of 30 占 퐉, a slurry was applied in a film form using a doctor blade method. Then, NMP in the slurry was volatilized and removed to form a negative electrode active material layer on the electrolytic copper foil. Subsequently, the electrolytic copper foil and the negative electrode active material layer were compressed using a roll press machine so that the thickness of the negative electrode active material layer was 20 占 퐉, thereby bonding the electrolytic copper foil and the negative electrode active material layer tightly.

Thereafter, the negative electrode active material layer in which NMP was removed and dried was subjected to a heat treatment in vacuum (under reduced pressure) at 180 DEG C for 3 hours to cause the intermediate composition contained in the negative electrode active material layer to undergo condensation reaction, The active material layer was cured by heating. Thus, an electrode sheet containing a polymer compound having a crosslinked structure as a negative electrode binder was obtained.

(Evaluation of Battery Characteristics)

The obtained electrode sheet was used to fabricate a lithium ion secondary battery, and the battery characteristics of the lithium ion secondary battery were evaluated. The results are shown in Table 8. The manufacturing method of the lithium ion secondary battery and the method of evaluating the battery characteristics of the lithium ion secondary battery are the same as those described above.

As shown in Table 8, in Test Examples 25 to 29 using Examples 4 to 8 as the negative electrode binder, the initial efficiency and the cycle characteristics together exhibited high values. From this result, it can be seen that, even when the position of the amino group, the presence or absence of other functional groups, and the structure of the Y portion are different, the polyfunctional amine having a structure satisfying the above-mentioned general formula (1) .

<Test 9>

Next, with respect to the negative electrode binder obtained from the intermediate composition (PAA + 4,4'-diaminodiphenylmethane) of Example 1, the change of the molecular structure in the course of heating and curing the intermediate composition was measured And analyzed by spectroscopic measurement.

First, a disk-shaped substrate having a diameter of 10 mm was obtained by pulverizing calcium fluoride. Next, about 10 占 퐇 of the NMP solution of the intermediate composition of Example 1 was dropped on one surface of the substrate under an argon atmosphere, and this was left to stand still for 24 hours and dried. Then, the substrate was dried in vacuum (under reduced pressure) Stopped and further dried. Thus, a measurement sample having a layer of an intermediate composition having a thickness of about 5 mu m was prepared on one side of the substrate of calcium fluoride. Measurement All samples were made at room temperature. Then, the obtained measurement sample was subjected to thermal scanning infrared spectroscopy (transmission method) to measure the change in the change of the peak showing the molecular structure on a time basis. The measurement conditions are as follows. Table 9 shows the results of the measurement.

Measurement apparatus: Fourier transform infrared spectrophotometer Cary 670 (manufactured by Agilent Technologies)

Measuring temperature: The temperature was raised from 30 占 폚 to the respective measuring temperature at a heating rate of 5 占 폚 / min, and then maintained at 200 占 폚 for 2 hours.

As shown in Table 9, the peak indicating the amide bond (CONH) started to be detected between 30 ° C and 125 ° C, and then gradually increased with the increase of the heating temperature. On the other hand, the peak showing the carboxyl group (COOH) and the peak showing the amine (NH ₂ ) gradually decreased with the rise of the heating temperature, and the peak indicating the amine particularly disappears at 150 ° C to 180 ° C. From these results, it can be seen that as the heating temperature rises, carboxyl groups and amines are consumed and amide bonds are formed.

Further, at 180 ° C to 200 ° C, a peak indicating an acid anhydride structure (CO-O-CO) was newly detected. This acid anhydride structure is considered to be a carboxylic acid anhydride formed by dehydration condensation of carboxyl groups not involved in formation of a crosslinked structure (amide bond) by heating at 180 ° C or higher. In <Test 4>, the effect of improving the cycle characteristics by increasing the heating temperature is shown. However, it is considered that the acid anhydride structure is formed as one of the factors for obtaining the improvement effect.

<Test 10>

Next, the dehydration condensation catalyst was used in the heat treatment of the negative electrode active material layer at the time of producing the electrode sheet, and the change in the battery characteristics when the heating time was different was evaluated.

(Preparation of electrode sheet)

70 parts by mass of the silicon material, 15 parts by mass of natural graphite, 5 parts by mass of acetylene black and 10 parts by mass of an NMP solution of the intermediate composition of Example 1-2 were mixed and NMP was added to the mixture to prepare a slurry. To the total amount of this slurry, 5 parts by mass of 1-methylimidazole was added as a dehydration condensation catalyst. The silicon material is a silicon material formed from a layered polysilane used in Test 5. The surface of the electrolytic copper foil of 30 占 퐉 as the current collector was coated with a slurry in the form of a film using a doctor blade method. Then, NMP in the slurry was volatilized and removed to form a negative electrode active material layer on the electrolytic copper foil. Subsequently, the electrolytic copper foil and the negative electrode active material layer were compressed using a roll press machine so that the thickness of the negative electrode active material layer was 20 占 퐉, thereby bonding the electrolytic copper foil and the negative electrode active material layer tightly.

Thereafter, the negative active material layer in which the NMP was removed and dried was subjected to heat treatment in vacuum (under reduced pressure) at different temperatures as shown in Table 10 for 2 hours to obtain a negative electrode active material layer The intermediate composition was subjected to condensation reaction, and the negative electrode active material layer was heated and cured. Thus, an electrode sheet containing a polymer compound having a crosslinked structure as a negative electrode binder was obtained. As a comparative object, an electrode sheet was prepared using a slurry to which a dehydration condensation catalyst was not added.

(Evaluation of Battery Characteristics)

The obtained electrode sheet was used to fabricate a lithium ion secondary battery, and the battery characteristics of the lithium ion secondary battery were evaluated. The results are shown in Table 10. The manufacturing method of the lithium ion secondary battery and the method of evaluating the battery characteristics of the lithium ion secondary battery are the same as those described above.

As shown in Table 10, in Test Examples 30 and 32 in which the heat treatment was performed in the presence of the dehydration condensation catalyst, the heat treatment temperature was lower than that of Test Examples 33 and 34 in which the heat treatment was performed in the absence of the dehydration condensation catalyst Despite the low efficiency, the initial efficiency and cycle characteristics were equal or more. Test Example 31 in which heat treatment was conducted in the presence of a dehydration condensation catalyst showed a significant improvement in cycle characteristics as compared with Test Example 34 in which heat treatment was performed under the same conditions in the absence of a dehydration condensation catalyst.

From these results, it was confirmed that the amidation reaction and the imidization reaction during the formation of the polymer compound were accelerated by the heat treatment in the presence of the dehydration condensation catalyst, and the objective crosslinked structure was obtained at a lower temperature.

<Test 11>

Next, the battery characteristics were evaluated in the case where PAA and a polymer compound obtained by condensing polyfunctional amine having a structure satisfying the above-mentioned general formula (1) and other polyfunctional amine were used as a negative electrode binder.

(Example 9: PAA + 4,4'-diaminodiphenylmethane + 1, 4-diaminobutane)

PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a 10 mass% PAA / NMP solution. 7 ml of this PAA / NMP solution (9.5 mmol in terms of monomer of PAA) was collected in a flask under a nitrogen atmosphere. Separately, an amine / NMP solution was prepared by dissolving 0.47 g (2.375 mmol) of 4,4'-diaminodiphenylmethane and 0.02 g (0.227 mmol) of 1,4-diaminobutane in 0.4 ml of NMP. While stirring the PAA / NMP solution in the flask, the total amount of the amine / NMP solution was dropped into the PAA / NMP solution, and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 9 was obtained in the form of an NMP solution by heat treatment (preheating treatment) at 130 占 폚 for 3 hours using a Dean-Stark apparatus.

(Example 10: PAA + 4,4'-diaminodiphenylmethane + 1, 6-diaminohexane)

PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a 10 mass% PAA / NMP solution. 7 ml of this PAA / NMP solution (9.5 mmol in terms of monomer of PAA) was collected in a flask under a nitrogen atmosphere. Separately, 0.47 g (2.375 mmol) of 4,4'-diaminodiphenylmethane and 0.02 g (0.172 mmol) of 1,6-diaminohexane were dissolved in 0.4 ml of NMP to prepare an amine / NMP solution . While stirring the PAA / NMP solution in the flask, the total amount of the amine / NMP solution was dropped into the PAA / NMP solution, and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 10 was obtained in the form of an NMP solution by heating treatment (preheating treatment) at 130 占 폚 for 3 hours using a Dean-Stark apparatus.

(Example 11: PAA + 4,4'-diaminodiphenylmethane + 3-aminoaniline)

PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a 10 mass% PAA / NMP solution. 7 ml of this PAA / NMP solution (9.5 mmol in terms of monomer of PAA) was collected in a flask under a nitrogen atmosphere. Separately, 0.47 g (2.375 mmol) of 4,4'-diaminodiphenylmethane and 0.02 g (0.185 mmol) of 3-aminoaniline were dissolved in 0.4 ml of NMP to prepare an amine / NMP solution. While stirring the PAA / NMP solution in the flask, the total amount of the amine / NMP solution was dropped into the PAA / NMP solution, and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 11 was obtained in the form of an NMP solution by heat treatment (preheating treatment) at 130 占 폚 for 3 hours using a Dean-Stark apparatus.

(Example 12: PAA + 4,4'-diaminodiphenylmethane + 2,6-diaminopyridine)

PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a 10 mass% PAA / NMP solution. 7 ml of this PAA / NMP solution (9.5 mmol in terms of monomer of PAA) was collected in a flask under a nitrogen atmosphere. Separately, 0.47 g (2.375 mmol) of 4,4'-diaminodiphenylmethane and 0.02 g (0.183 mmol) of 2,6-diaminopyridine were dissolved in 0.4 ml of NMP to prepare an amine / NMP solution . While stirring the PAA / NMP solution in the flask, the total amount of the amine / NMP solution was dropped into the PAA / NMP solution, and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 12 was obtained in the form of an NMP solution by a heat treatment (preheating treatment) at 130 占 폚 for 3 hours using a Dean-Stark apparatus.

(Example 13: PAA + 4,4'-diaminodiphenylmethane + 1,3-diiminoisoindoline)

PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a 10 mass% PAA / NMP solution. 7 ml of this PAA / NMP solution (9.5 mmol in terms of monomer of PAA) was collected in a flask under a nitrogen atmosphere. Separately, 0.47 g (2.375 mmol) of 4,4'-diaminodiphenylmethane and 0.02 g (0.137 mmol) of 1,3-diiminoisoindoline were dissolved in 0.4 ml of NMP, and an amine / NMP solution Lt; / RTI &gt; While stirring the PAA / NMP solution in the flask, the total amount of the amine / NMP solution was dropped into the PAA / NMP solution, and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 13 was obtained in the form of an NMP solution by heating treatment (preheating treatment) at 130 占 폚 for 3 hours using a Dean-Stark apparatus.

(Preparation of electrode sheet)

70 parts by mass of the silicone material, 15 parts by mass of natural graphite, 5 parts by mass of acetylene black and 10 parts by mass of an NMP solution of the intermediate composition of Examples 9 to 13 were mixed and NMP was added to the mixture to prepare a slurry. To the total amount of the slurry, 5 parts by mass of 1-methylimidazole was added. The silicon material is a silicon material formed from a layered polysilane used in Test 5. The surface of the electrolytic copper foil of 30 占 퐉 as the current collector was coated with a slurry in the form of a film using a doctor blade method. Then, NMP in the slurry was volatilized and removed to form a negative electrode active material layer on the electrolytic copper foil. Subsequently, the electrolytic copper foil and the negative electrode active material layer were compressed using a roll press machine so that the thickness of the negative electrode active material layer was 20 占 퐉, thereby bonding the electrolytic copper foil and the negative electrode active material layer tightly.

Thereafter, the negative electrode active material layer in which NMP was removed and dried was subjected to a heat treatment in vacuum (under reduced pressure) at 180 DEG C for 2 hours to cause the intermediate composition contained in the negative electrode active material layer to undergo a condensation reaction, The active material layer was cured by heating. Thus, an electrode sheet containing a polymer compound having a crosslinked structure as a negative electrode binder was obtained.

(Evaluation of Battery Characteristics)

The obtained electrode sheet was used to fabricate a lithium ion secondary battery, and the battery characteristics of the lithium ion secondary battery were evaluated. The results are shown in Table 11. The manufacturing method of the lithium ion secondary battery and the method of evaluating the battery characteristics of the lithium ion secondary battery are the same as those described above.

As shown in Table 11, in the test examples 35 to 39 using the examples 9 to 13 in which the polyfunctional amine having the structure satisfying the above-mentioned general formula (1) was condensed with the other polyfunctional amine as the negative electrode binder Was equal to or higher than the initial efficiency and cycle characteristics in Test Example 30 using the positive electrode binder as the negative electrode binder. From these results, it was confirmed that the polymer compound in which other polyfunctional amine is condensed is equally useful as a negative electrode binder of a power storage device such as a secondary battery.

<Test 12>

Next, when a polymer compound obtained by condensing PAA with a polyfunctional amine having a structure satisfying the above-mentioned general formula (1) and other polyfunctional amines is used as a negative electrode binder, mixing of other polyfunctional amines The change in the battery characteristics when the ratios were different was evaluated.

(Examples 11-1 to 11-3: PAA + 4,4'-diaminodiphenylmethane + 3-aminoaniline)

An intermediate composition of Examples 11-1 to 11-3 was obtained by varying the amount of 3-aminoaniline (other polyfunctional amine) added to the intermediate composition of Example 11. Amounts of 3-aminoaniline in each of the examples are as shown in the column of other polyfunctional amines in Table 12. Examples 11-1 to 11-3 were prepared in the same manner as in Example 11, except that the amounts of 3-aminoaniline were different.

(Battery evaluation)

Using the intermediate compositions of Examples 11-1 to 11-3, an electrode sheet was produced using the polymer compound obtained from the intermediate composition as a negative electrode binder. The manufacturing method of the electrode sheet is the same as that of the test 11. The obtained electrode sheet was used to fabricate a lithium ion secondary battery, and the battery characteristics of the lithium ion secondary battery were evaluated. The results are shown in Table 12. The manufacturing method of the lithium ion secondary battery and the method of evaluating the battery characteristics of the lithium ion secondary battery are the same as those described above.

As shown in Table 12, it was confirmed that the initial efficiency and cycle characteristics were lowered as the blending amount of other polyfunctional amine was increased. It is considered that if the cross-linking structure derived from other polyfunctional amines in the polymer compound is excessively large, the cross-linking state of the polymer compound is greatly changed, and the property of the negative electrode as a binder is lowered. From these results, it is suggested that when a crosslinking structure derived from other polyfunctional amine is given, it is preferable to limit the crosslinking structure to a certain amount or less.

<Test 13>

Next, when a polymer compound obtained by condensing PAA and a polyfunctional amine having a structure satisfying the above-mentioned general formula (1) is used as a negative electrode binder, the change in cell characteristics when the molecular weight of PAA is varied .

(Examples 1-5 to 1-7: PAA + 4,4'-diaminodiphenylmethane)

By using PAA having different molecular weights (weight average molecular weight) for the intermediate composition of Example 1, intermediate compositions of Examples 1-5 to 1-7 were obtained. The molecular weight of PAA in each example is as shown in the column of the molecular weight of PAA in Table 13. Examples 1-5 to 1-7 were prepared in the same manner as in Example 1 except that the molecular weight of PAA was different. The polyacrylic acid of each example was manufactured by Wako Pure Chemical Industries, Ltd.

(Battery evaluation)

Using the intermediate compositions of Examples 1-5 to 1-7, an electrode sheet was prepared using the polymer compound obtained from the intermediate composition as a negative electrode binder. The active material and the method for producing the electrode sheet are the same as those in Test 5. The obtained electrode sheet was used to fabricate a lithium ion secondary battery, and the battery characteristics of the lithium ion secondary battery were evaluated. The results are shown in Table 13. The manufacturing method of the lithium ion secondary battery and the method of evaluating the battery characteristics of the lithium ion secondary battery are the same as those described above.

As shown in Table 13, even when the molecular weights of PAA were different, no significant difference was observed in the battery characteristics. From these results, it was found that the crosslinking structure of the polymer compound (for example, the amine structure of the crosslinking site, the amide structure and the imide structure of the crosslinking site) of the polymer compound obtained from the intermediate composition of the Examples is important , And the length of the chain-like structure constituted by PAA has no substantial influence.

Further, when an intermediate composition was prepared using PAA having a molecular weight of 9000, precipitation of a solid in the liquid was confirmed. From these results, it is suggested that it is preferable to use PAA having a certain molecular weight or more from the viewpoint of easy preparation of the intermediate composition.

<Test 14>

Next, changes in the properties of the slurry and changes in battery characteristics were evaluated in the case where the molecular weight of the polymer compound as the negative electrode binder was changed.

(Example 14: PAA + 4,4'-diaminodiphenylmethane)

A PAA / NMP solution having a solid content concentration of 7 mass% of PAA was prepared by dissolving PAA having a weight average molecular weight of 800,000 in NMP, and 6 g of this PAA / NMP solution (5.83 mmol in terms of monomer of PAA) And collected in a flask. Separately, 4,4'-diaminodiphenylmethane was dissolved in NMP to prepare an amine / NMP solution of 50 mass%. While stirring the PAA / NMP solution in the flask, 0.577 g (1.47 mmol) of an amine / NMP solution was added dropwise to the PAA / NMP solution, and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 14 was obtained in the state of NMP solution (solid content ratio of 10.8 mass%, viscosity of 3000 cP) by heating treatment (preheating treatment) at 110 캜 for 3 hours using a Dean Stark apparatus .

(Example 15: PAA + 4,4'-diaminodiphenylmethane)

PAA having a weight average molecular weight of 250,000 was dissolved in NMP to prepare a PAA / NMP solution having a solid content concentration of PAA of 15 mass%, and 6 g of this PAA / NMP solution (12.5 mmol in terms of monomer of PAA) And collected in a flask. Separately, 4,4'-diaminodiphenylmethane was dissolved in NMP to prepare an amine / NMP solution of 50 mass%. While stirring the PAA / NMP solution in the flask, 1.236 g (3.13 mmol) of amine / NMP solution was added dropwise to the PAA / NMP solution, and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 15 was obtained in the state of NMP solution (solid content ratio of 21 mass%, viscosity of 3000 cP) by heating treatment (preheating treatment) at 110 캜 for 3 hours by using a Dean Stark apparatus .

(Example 16: PAA + 4,4'-diaminodiphenylmethane)

The PAA aqueous solution having a weight average molecular weight of 100,000 was subjected to vacuum drying and solvent substitution with acetone to remove moisture until the water content became 1% by mass or less. The water-removed PAA was dissolved in NMP to prepare a PAA / NMP solution having a solid content concentration of PAA of 20 mass%, and 6 g of this PAA / NMP solution (16.7 mmol in terms of monomer of PAA) Lt; / RTI &gt; Separately, 4,4'-diaminodiphenylmethane was dissolved in NMP to prepare an amine / NMP solution of 50 mass%. While stirring the PAA / NMP solution in the flask, 1.648 g (4.16 mmol) of the amine / NMP solution was added dropwise to the PAA / NMP solution and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 16 was obtained in the form of an NMP solution (solid content ratio 26.5 mass%, viscosity 3000 cP) by heating treatment (preheating treatment) at 110 캜 for 3 hours using a Dean Stark apparatus .

(Example 17: PAA + 4,4'-diaminodiphenylmethane)

The PAA aqueous solution having a weight average molecular weight of 50,000 was subjected to vacuum drying and solvent substitution by acetone to remove moisture until the water content became 1% by mass or less. The water-removed PAA was dissolved in NMP to prepare a PAA / NMP solution having a solid content concentration of PAA of 24% by mass, and 6 g of this PAA / NMP solution (20.0 mmol in terms of monomer of PAA) Lt; / RTI &gt; Separately, 4,4'-diaminodiphenylmethane was dissolved in NMP to prepare an amine / NMP solution of 50 mass%. While stirring the PAA / NMP solution in the flask, 1.978 g (5.0 mmol) of the amine / NMP solution was added dropwise to the PAA / NMP solution and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 17 was obtained as an NMP solution (solid content ratio: 30.4% by mass, viscosity: 3000 cP) by a heat treatment (preheating treatment) at 110 캜 for 3 hours using a Dean Stark apparatus .

(Example 18: PAA + 4,4'-diaminodiphenylmethane)

PAA having a weight average molecular weight of 25,000 was dissolved in NMP to prepare a PAA / NMP solution having a solid content concentration of PAA of 30% by mass, and 6 g of this PAA / NMP solution (25.0 mmol in terms of monomer of PAA) And collected in a flask. Separately, 4,4'-diaminodiphenylmethane was dissolved in NMP to prepare an amine / NMP solution of 50 mass%. While stirring the PAA / NMP solution in the flask, 2.472 g (6.25 mmol) of the amine / NMP solution was added dropwise to the PAA / NMP solution and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 18 was obtained in the form of an NMP solution (solid content ratio: 35.8 mass%, viscosity: 3000 cP) by heating treatment (preheating treatment) at 110 ° C for 3 hours using a Dean Stark apparatus .

In addition, as a reference example, changes in the properties of the slurry and changes in battery characteristics were evaluated in the case where the molecular weights of the PAI as the negative electrode binder were different.

(Reference Example 4: PAI)

A first NMP solution was prepared by dissolving 2.503 g (10 mmol) of 4,4'-methylene diphenyl diisocyanate in 17.5 g of NMP. Separately, 1.92 g (10 mmol) of trimellitic anhydride chloride was dissolved in 13.4 g of NMP to prepare a second NMP solution. A second NMP solution was added to the first NMP solution under an inert gas atmosphere, and the mixture was heat-treated at 90 占 폚 for 5 hours to obtain an NMP solution (solid content ratio: 12.5 mass%, viscosity 200 cP) of PAI having a molecular weight of 20,000.

(Reference Example 5: PAI)

A first NMP solution was prepared by dissolving 2.503 g (10 mmol) of 4,4'-methylene diphenyl diisocyanate in 11.4 g of NMP. Separately, 1.92 g (10 mmol) of trimellitic anhydride chloride was dissolved in 8.75 g of NMP to prepare a second NMP solution. A second NMP solution was added to the first NMP solution under an inert gas atmosphere and the mixture was heat-treated at 80 DEG C for 3 hours to obtain an NMP solution (solid content ratio of 18 mass%, viscosity 180 cP) of PAI having a molecular weight of 5,000.

(Preparation of electrode sheet)

85 parts by mass of the silicone material, 5 parts by mass of acetylene black, 10 parts by mass of the NMP solution of Examples 14 to 18 and Reference Examples 4 and 5 were mixed and NMP was added to the mixture to give a viscosity of 2500 cP To prepare a slurry. Table 14 shows the total solid content ratio of this slurry. Then, on the surface of the electrolytic copper foil of 30 占 퐉 as the current collector, the slurry was applied in the form of a film using the doctor blade method. Then, the electrolytic copper foil was stopped at 80 DEG C for 15 minutes on a hot plate, and the NMP in the slurry was removed by volatilization to form a negative electrode active material layer on the electrolytic copper foil. Subsequently, the electrolytic copper foil and the negative electrode active material layer were compressed using a roll press machine so that the thickness of the negative electrode active material layer was 20 占 퐉, thereby bonding the electrolytic copper foil and the negative electrode active material layer tightly. This electrode sheet was cut to a diameter of 11 mm to form an electrode body, which was heat-treated in vacuum (under reduced pressure) at 180 DEG C for 2 hours to heat and cure the negative electrode active material layer.

Also, the mass of the electrode body was measured before and after the heat curing treatment, and the amount of decrease before and after the heat curing treatment was obtained. The remaining amount of the solvent contained in the negative electrode active material layer before the heat curing treatment was calculated on the assumption that all of the decrease in mass after the heat curing treatment was caused by volatilization of the solvent.

(Battery evaluation)

The obtained electrode sheet was used to fabricate a lithium ion secondary battery, and the battery characteristics of the lithium ion secondary battery were evaluated. Table 14 shows the results. The manufacturing method of the lithium ion secondary battery and the method of evaluating the battery characteristics of the lithium ion secondary battery are the same as those described above.

As shown in Table 14, similar to the results of Test 13, in Test Examples 46 to 50 using the examples, even when the molecular weights of PAA were different, no significant difference in battery characteristics was found. On the other hand, with respect to Test Examples 51 and 52 using the reference example, the cycle characteristics decreased with the decrease in the molecular weight of PAI. From these results, it is suggested that the polymer compound obtained from the intermediate composition of the Examples is less likely to lower the resin strength as the molecular weight is lowered as compared with PAI.

With respect to Test Examples 46 to 50 using the examples, the residual amount of the solvent contained in the negative electrode active material layer before the heat curing treatment was lowered due to the decrease in molecular weight of PAA. This result is considered to be due to the fact that the amount of the solvent required for preparing the slurry is reduced by setting the molecular weight of the polymer compound based on the lowering of the molecular weight of the PAA and the total solid content ratio of the slurry can be set to a large value.

<Test 15>

Next, when the polymer compound of the present embodiment was used as the negative electrode binder and the mixing ratio of the negative electrode active material and the negative electrode binder to the electrode sheet using the silicon material (see Test 5) as the negative electrode active material was changed Were evaluated for changes in battery characteristics.

(Preparation of electrode sheet)

The above silicon material, natural graphite, acetylene black, NMP solution (intermediate binder binder) of the intermediate composition of Example 1 were mixed at the compounding ratio (mass ratio) shown in Table 15 and NMP was added to the mixture to prepare a slurry Respectively. The subsequent steps are the same as those of Test 5.

(Battery evaluation)

The obtained electrode sheet was used to fabricate a lithium ion secondary battery, and the battery characteristics of the lithium ion secondary battery were evaluated. Table 15 shows the results. The manufacturing method of the lithium ion secondary battery and the method of evaluating the battery characteristics of the lithium ion secondary battery are the same as those described above.

As shown in Table 15, it was confirmed that the battery characteristics were changed according to the blending ratio of the negative electrode active material and the negative electrode binder. Particularly, when the binder ratio for the negative electrode active material / negative electrode is 7.5 or less, the initial efficiency and cycle characteristics are greatly improved, and when the binder ratio for the negative electrode active material / negative electrode is in the range of 4 to 5, It was confirmed that it was improved.

<Test 16>

Next, the electrode sheet using the polymer compound of the present embodiment as the negative electrode binder was evaluated for changes in the properties of the slurry and changes in battery characteristics when the particle diameter of the acetylene black contained as the conductive auxiliary agent was changed.

(Preparation of electrode sheet)

Acetylene black powder, polyvinyl pyrrolidone (dispersant) and NMP were added into a pot of a planetary ball mill (LMZ015, manufactured by Ashizawa Co., Ltd.), acetylene black was pulverized by an oil-based ball mill, To prepare a dispersion. At this time, a plurality of NMP dispersions having different acetylene black particle diameters were prepared by changing the treatment time by the planetary ball mill. Table 16 shows the particle diameters (D10, D50, D90) of acetylene black in each NMP dispersion.

72.5 parts by mass of the silicone material, 13.5 parts by mass of the acetylene black and 14 parts by mass of the NMP solution of the intermediate composition of Example 1 were mixed and NMP was added to the mixture to prepare a slurry. The subsequent steps are the same as those of Test 5. The viscosity of the prepared slurry was measured, and the electrode resistance of the obtained electrode sheet was measured.

(Battery evaluation)

The obtained electrode sheet was used to fabricate a lithium ion secondary battery, and the battery characteristics of the lithium ion secondary battery were evaluated. The results are shown in Table 16. The manufacturing method of the lithium ion secondary battery and the method of evaluating the battery characteristics of the lithium ion secondary battery are the same as those described above.

As shown in Table 16, it was confirmed that the battery characteristics were changed according to the particle diameter of the acetylene black. As a cause of lowering the cycle characteristics in Test Example 61 in which acetylene black has a large particle diameter, it is considered that the slurry used in the production of the electrode is a slurry having a high viscosity and a poor dispersibility. In Test Example 61, acetylene black not subjected to pulverization by an oil-based ball mill was used. In addition, in the test example 65 in which acetylene black has a small particle diameter, the initial efficiency, the cycle characteristics, and the electrode resistance increase are caused by excessive ball milling due to the planetary ball mill ), It is considered that the structure collapse of the acetylene black and the formation of the new surface proceed to cut off or re-agglomerate the conduction path.

<Test 17>

Next, the electrode sheet using the polymer compound of the present embodiment as the negative electrode binder was evaluated for the change in battery characteristics when the blending ratio of acetylene black contained as a conductive auxiliary agent and negative electrode binder was varied.

(Preparation of electrode sheet)

The above silicon material, natural graphite, acetylene black and NMP solution (intermediate binder binder) of the intermediate composition of Example 1 were mixed in the mixing ratio (mass ratio) shown in Table 17, and NMP was added to this mixture to prepare a slurry Respectively. The subsequent steps are the same as those of Test 5. As the acetylene black, those having the same particle diameters as in Test Example 63 were used.

(Battery evaluation)

The obtained electrode sheet was used to fabricate a lithium ion secondary battery, and the battery characteristics of the lithium ion secondary battery were evaluated. The results are shown in Table 17. The manufacturing method of the lithium ion secondary battery and the method of evaluating the battery characteristics of the lithium ion secondary battery are the same as those described above.

As shown in Table 17, it was confirmed that the battery characteristics were changed according to the blending ratio of acetylene black to negative electrode binder. In particular, when the binder ratio for the acetylene black / negative electrode was set to 0.5 or more, the cycle characteristics were greatly improved, and it was confirmed that the initial efficiency was greatly improved when the ratio was 1.5 or less.

<Test 18>

Next, the electrode sheet using the polymer compound of the present embodiment as the negative electrode binder was evaluated for changes in the battery characteristics when a plurality of conductive auxiliary agents were used in combination.

(Preparation of electrode sheet)

The NMP solution (negative electrode binder) of the silicone material, natural graphite, acetylene black, carbon nanotubes and the intermediate composition of Example 1 was mixed at the compounding ratio (mass ratio) shown in Table 18, and NMP was added To prepare a slurry. NMP solution (negative electrode binder) of the above-mentioned silicone material, natural graphite, acetylene black, Ketjenblack and the intermediate composition of Example 1 was mixed in the mixing ratio (mass ratio) shown in Table 19, and NMP To prepare a slurry. The subsequent steps are the same as those of Test 5. As the acetylene black, those having the same particle diameters as in Test Example 63 were used.

(Battery evaluation)

The obtained electrode sheet was used to fabricate a lithium ion secondary battery, and the battery characteristics of the lithium ion secondary battery were evaluated. The results are shown in Table 17. The manufacturing method of the lithium ion secondary battery and the method of evaluating the battery characteristics of the lithium ion secondary battery are the same as those described above.

As shown in Table 18, it was confirmed that even when the acetylene black and the carbon nanotube were used together as the conductive auxiliary agent, an effect of improving the battery characteristics was obtained. In particular, when the carbon nanotubes were used in combination with the acetylene black alone, it was confirmed that the cycle characteristics were improved.

As shown in Table 19, it was confirmed that even when acetylene black and ketjen black were used in combination as the conductive auxiliary agent, an effect of improving battery characteristics was obtained. Especially, when the ketjen black was used in combination with the acetylene black alone, it was confirmed that the cycle characteristics were improved.

<Test 19>

Next, the battery characteristics in the case where PAA and a polymer compound obtained by condensing a polyfunctional carboxylic acid having a structure satisfying the above-mentioned general formula (1) and a polyfunctional carboxylic acid were used as a negative electrode binder were evaluated.

(Example 19: PAA + 1,2,3-propanetricarboxylic acid + 4,4'-diaminodiphenylmethane)

A PAA / NMP solution of 10 mass% was prepared by dissolving PAA having a weight average molecular weight of 800,000 in NMP, and 60 g of this PAA / NMP solution (83.3 mmol in terms of monomer of PAA) was collected in a flask under a nitrogen atmosphere. 0.38 g (2.1 mmol) of 1,2,3-propanetricarboxylic acid was added to this solution, and the mixture was stirred at room temperature for 30 minutes to prepare a PAA-carboxylic acid / NMP solution. Separately, 4.1 g (20.70 mmol) of 4,4'-diaminodiphenylmethane was dissolved in 5 ml of NMP to prepare an amine / NMP solution. While stirring the PAA-carboxylic acid / NMP solution in the flask, the entire amount of the amine / NMP solution was added dropwise, and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 19 was obtained in the form of an NMP solution by a heat treatment (preheating treatment) at 130 占 폚 for 3 hours using a Dean-Stark apparatus.

(Example 20: PAA + meso-1,2,3,4-butanetetracarboxylic acid + 4,4'-diaminodiphenylmethane)

A PAA / NMP solution of 10 mass% was prepared by dissolving PAA having a weight average molecular weight of 800,000 in NMP, and 60 g of this PAA / NMP solution (83.3 mmol in terms of monomer of PAA) was collected in a flask under a nitrogen atmosphere. 0.5 g (2.1 mmol) of 1,2,3-propanetricarboxylic acid was added to this solution, and the mixture was stirred at room temperature for 30 minutes to prepare a PAA-carboxylic acid / NMP solution. Separately, 4.1 g (20.70 mmol) of 4,4'-diaminodiphenylmethane was dissolved in 5 ml of NMP to prepare an amine / NMP solution. While stirring the PAA-carboxylic acid / NMP solution in the flask, the entire amount of the amine / NMP solution was added dropwise, and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 20 was obtained in the form of an NMP solution by a heat treatment (preheating treatment) at 130 占 폚 for 3 hours using a Dean-Stark apparatus.

(Example 21: PAA + trimellitic acid + 4,4'-diaminodiphenylmethane)

A PAA / NMP solution of 10 mass% was prepared by dissolving PAA having a weight average molecular weight of 800,000 in NMP, and 60 g of this PAA / NMP solution (83.3 mmol in terms of monomer of PAA) was collected in a flask under a nitrogen atmosphere. 0.45 g (2.1 mmol) of trimellitic acid was added to this solution, and the mixture was stirred at room temperature for 30 minutes to prepare a PAA-carboxylic acid / NMP solution. Separately, 4.1 g (20.70 mmol) of 4,4'-diaminodiphenylmethane was dissolved in 5 ml of NMP to prepare an amine / NMP solution. While stirring the PAA-carboxylic acid / NMP solution in the flask, the entire amount of the amine / NMP solution was added dropwise, and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 21 was obtained in the form of an NMP solution by heating (preheating treatment) at 130 캜 for 3 hours using a Dean-Stark apparatus.

(Example 22: PAA + pyromellitic acid + 4,4'-diaminodiphenylmethane)

A PAA / NMP solution of 10 mass% was prepared by dissolving PAA having a weight average molecular weight of 800,000 in NMP, and 60 g of this PAA / NMP solution (83.3 mmol in terms of monomer of PAA) was collected in a flask under a nitrogen atmosphere. 0.54 g (2.1 mmol) of pyromellitic acid was added to this solution, and the mixture was stirred at room temperature for 30 minutes to prepare a PAA-carboxylic acid / NMP solution. Separately, 4.1 g (20.70 mmol) of 4,4'-diaminodiphenylmethane was dissolved in 5 ml of NMP to prepare an amine / NMP solution. While stirring the PAA-carboxylic acid / NMP solution in the flask, the entire amount of the amine / NMP solution was added dropwise, and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 22 was obtained in the form of an NMP solution by heat treatment (preheating treatment) at 130 占 폚 for 3 hours using a Dean-Stark apparatus.

(Preparation of electrode sheet)

70 parts by mass of the silicone material, 15 parts by mass of natural graphite, 5 parts by mass of acetylene black, 10 parts by mass of the NMP solution of the intermediate composition of Example 1-2 and Examples 19 to 22 were mixed and NMP was added to the mixture To prepare a slurry. The silicon material is a silicon material formed from a layered polysilane used in Test 5. The surface of the electrolytic copper foil of 30 占 퐉 as the current collector was coated with a slurry in the form of a film using a doctor blade method. Then, NMP in the slurry was volatilized and removed to form a negative electrode active material layer on the electrolytic copper foil. Subsequently, the electrolytic copper foil and the negative electrode active material layer were compressed using a roll press machine so that the thickness of the negative electrode active material layer was 20 占 퐉, thereby bonding the electrolytic copper foil and the negative electrode active material layer tightly.

Thereafter, the negative electrode active material layer in which NMP was removed and dried was heat-treated in a vacuum (under reduced pressure) at 180 DEG C for 2 hours to condense the intermediate composition contained in the negative electrode active material layer , And the negative electrode active material layer was heated and cured. Thus, an electrode sheet containing a polymer compound having a crosslinked structure as a negative electrode binder was obtained.

(Evaluation of Battery Characteristics)

The obtained electrode sheet was used to fabricate a lithium ion secondary battery, and the battery characteristics of the lithium ion secondary battery were evaluated. Table 20 shows the results. The manufacturing method of the lithium ion secondary battery and the method of evaluating the battery characteristics of the lithium ion secondary battery are the same as those described above.

As shown in Table 20, also in the test examples 86 to 89 using the examples 19 to 22 in which the multifunctional carboxylic acid was condensed as the binder for the negative electrode, the same test examples as those of the test example 90 using the example 1-2 as the negative electrode binder An effect of improving the battery characteristics was obtained. From the results of Test Examples 86 to 89, it was found that, in the case of using a polyfunctional carboxylic acid having a flexible chain structure (Test Examples 86 and 87), the initial efficiency was improved and the polyfunctional car In the case of using the carboxylic acid (Test Examples 88 and 89), it was confirmed that the cycle characteristics were improved. These results suggest that the properties of the polymer compound can be controlled by adding a crosslinking structure derived from a polyfunctional carboxylic acid.

<Test 20>

Next, when a polymer compound obtained by condensing PAA with a polyfunctional carboxylic acid having a structure satisfying the above-mentioned general formula (1) and a polyfunctional carboxylic acid is used as a negative electrode binder, a polyfunctional carboxylic acid The change in the battery characteristics when the blend ratio was different was evaluated.

(Examples 20-1 to 20-5: PAA + meso-1,2,3,4-butanetetracarboxylic acid + 4,4'-diaminodiphenylmethane)

With respect to the intermediate composition of Example 20, the amount of the polyfunctional carboxylic acid was varied to obtain an intermediate composition of Examples 20-1 to 20-5 in which the mixing ratio of the polyfunctional carboxylic acid was different. The blending amount of the polyfunctional carboxylic acid in each example is as shown in the column of the polyfunctional carboxylic acid in Table 21. Examples 20-1 to 20-5 were prepared in the same manner as in Example 20, except that the amount of meso-1,2,3,4-butanetetracarboxylic acid as the polyfunctional carboxylic acid was varied Respectively.

(Battery evaluation)

Using the intermediate compositions of Examples 20-1 to 20-5, an electrode sheet having a negative electrode binder as a polymer compound obtained from the intermediate composition was prepared. The method of producing the electrode sheet is the same as that of Test 19. The obtained electrode sheet was used to fabricate a lithium ion secondary battery, and the battery characteristics of the lithium ion secondary battery were evaluated. The results are shown in Table 21. The manufacturing method of the lithium ion secondary battery and the method of evaluating the battery characteristics of the lithium ion secondary battery are the same as those described above.

As shown in Table 21, it was confirmed that the initial efficiency was improved as the blending amount of the polyfunctional carboxylic acid was decreased. When the crosslinking structure derived from the polyfunctional carboxylic acid structure is small in the polymer compound, the flexibility of the crosslinked structure is high, so that it is considered that the intercalation / release of lithium can be efficiently carried out.

On the other hand, it was confirmed that as the blending amount of the polyfunctional carboxylic acid increases, the cycle characteristics tend to be improved. When the cross-linking structure derived from the polyfunctional carboxylic acid structure is large in the polymer compound, the cross-linking structure becomes strong, and thus the cycle characteristics are considered to be high.

From these results, it is suggested that when a crosslinking structure derived from a polyfunctional carboxylic acid is added, it is preferable to restrict the crosslinking structure to a certain amount or less.

<Test 21>

Next, the battery characteristics were evaluated in the case where PAA and a polymer compound comprising a polyfunctional amine having a structure satisfying the above-mentioned general formula (1) and a monoamine were used as a negative electrode binder.

(Example 23: PAA + 4,4'-diaminodiphenylmethane + aniline)

A PAA / NMP solution of 10 mass% was prepared by dissolving PAA having a weight average molecular weight of 800,000 in NMP, and 60 g of this PAA / NMP solution (83.3 mmol in terms of monomer of PAA) was collected in a flask under a nitrogen atmosphere. Separately, 4.1 g (20.70 mmol) of 4,4'-diaminodiphenylmethane and 251 mg (0.207 mmol) of aniline were dissolved in 5 ml of NMP to prepare a mixed amine / NMP solution. While stirring the PAA / NMP solution in the flask, the total amount of the mixed amine / NMP solution was added dropwise, and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 23 was obtained in the form of an NMP solution by a heat treatment (preheating treatment) at 130 DEG C for 3 hours using a Dean-Stark apparatus.

(Example 24: PAA + 4,4'-diaminodiphenylmethane + aminophenol)

A PAA / NMP solution of 10 mass% was prepared by dissolving PAA having a weight average molecular weight of 800,000 in NMP, and 60 g of this PAA / NMP solution (83.3 mmol in terms of monomer of PAA) was collected in a flask under a nitrogen atmosphere. Separately, 4.1 g (20.70 mmol) of 4,4'-diaminodiphenylmethane and 226 mg (0.207 mmol) of aminophenol were dissolved in 5 ml of NMP to prepare a mixed amine / NMP solution. While stirring the PAA / NMP solution in the flask, the total amount of the mixed amine / NMP solution was added dropwise, and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 23 was obtained in the form of an NMP solution by a heat treatment (preheating treatment) at 130 DEG C for 3 hours using a Dean-Stark apparatus.

(Example 25: PAA + 4,4'-diaminodiphenylmethane + morpholine)

A PAA / NMP solution of 10 mass% was prepared by dissolving PAA having a weight average molecular weight of 800,000 in NMP, and 60 g of this PAA / NMP solution (83.3 mmol in terms of monomer of PAA) was collected in a flask under a nitrogen atmosphere. Separately, 4.1 g (20.70 mmol) of 4,4'-diaminodiphenylmethane and 180 mg (0.207 mmol) of morpholine were dissolved in 5 mL of NMP to prepare a mixed amine / NMP solution. While stirring the PAA / NMP solution in the flask, the total amount of the mixed amine / NMP solution was added dropwise, and stirring was continued at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 23 was obtained in the form of an NMP solution by a heat treatment (preheating treatment) at 130 DEG C for 3 hours using a Dean-Stark apparatus.

(Preparation of electrode sheet)

70 parts by mass of the silicone material, 15 parts by mass of natural graphite, 5 parts by mass of acetylene black, 10 parts by mass of an NMP solution of the intermediate composition of Examples 1-2 and Examples 23 to 25 were mixed and NMP was added to the mixture To prepare a slurry. The silicon material is a silicon material formed from a layered polysilane used in Test 5. The surface of the electrolytic copper foil of 30 占 퐉 as the current collector was coated with a slurry in the form of a film using a doctor blade method. Then, NMP in the slurry was volatilized and removed to form a negative electrode active material layer on the electrolytic copper foil. Subsequently, the electrolytic copper foil and the negative electrode active material layer were compressed using a roll press machine so that the thickness of the negative electrode active material layer was 20 占 퐉, thereby bonding the electrolytic copper foil and the negative electrode active material layer tightly.

Thereafter, the negative electrode active material layer in which NMP was removed and dried was heat-treated in a vacuum (under reduced pressure) at 180 DEG C for 2 hours to condense the intermediate composition contained in the negative electrode active material layer , And the negative electrode active material layer was heated and cured. Thus, an electrode sheet containing a polymer compound having a crosslinked structure as a negative electrode binder was obtained.

(Evaluation of Battery Characteristics)

The obtained electrode sheet was used to fabricate a lithium ion secondary battery, and the battery characteristics of the lithium ion secondary battery were evaluated. Table 20 shows the results. The manufacturing method of the lithium ion secondary battery and the method of evaluating the battery characteristics of the lithium ion secondary battery are the same as those described above.

As shown in Table 22, also in the test examples 96 to 98 using the examples 23 to 25 in which the monoamine was condensed as the negative electrode binder, battery characteristics equivalent to or higher than those of the test example 90 using the example 1-2 as the negative electrode binder Was obtained. Particularly, in the test examples 96 to 98 using the examples 23 to 25 in which the monoamines were condensed, the tendency to show higher initial efficiency than that in the test example 90 using the example 1-2. This tendency is considered to be due to the following mechanism. That is, in the molecular structure of the polymer compound, the free amino group is reduced by the binding of the monoamine to the carboxyl group, and the aggregation of the polymer compound due to the hydrogen bond of the carboxyl group is suppressed. Thereby, the permeability of lithium ions is increased, and the insertion and release of lithium is efficiently carried out.

From this result, not only the crosslinking water was adjusted based on the carboxyl / amino group ratio shown in Test 2, but also by chemically terminating the carboxyl group by bonding monoamine to reduce the hydrogen bonding of the polymer compound, We can confirm that the characteristics can be controlled.

Claims (25)

As a polymer compound to be used as a negative electrode binder of a power storage device,
The polymer compound is a compound obtained by condensing polyacrylic acid with a polyfunctional amine represented by the following general formula (1)
Y is a linear alkyl group having 1 to 4 carbon atoms, a phenylene group, or an oxygen atom, and each of R 1 and R 2 is independently a hydrogen atom, a methyl group, an ethyl group, a trifluoromethyl group or a methoxy group Lt; / RTI &gt;
[Chemical Formula 1]

The method according to claim 1,
The polymer compound has an acid anhydride structure. As a polymer compound to be used as a negative electrode binder of a power storage device,
And a cross-linking structure for connecting the carboxylic acid side chains between the chain-like structure and the chain-like structure formed by polyacrylic acid,
The crosslinking structure is at least one crosslinking structure selected from the following general formulas (2) to (4)
PAA represents a chain-like structure composed of polyacrylic acid, X represents a structure represented by the following general formula (5)
Y is a linear alkyl group having 1 to 4 carbon atoms, a phenylene group, or an oxygen atom, and each of R 1 and R 2 is independently a hydrogen atom, a methyl group, an ethyl group, a trifluoromethyl group or a methoxy group Lt; / RTI &gt;
(2)

(3)

The method of claim 3,
Wherein the polymer compound has at least a crosslinked structure of the general formula (2) and the general formula (4) or a crosslinked structure of the general formula (3) as the crosslinked structure. The method of claim 3,
The polymer compound has an acid anhydride structure. An intermediate composition for a polymer compound used as a binder for a negative electrode of a power storage device,
A polyacrylic acid, a polyfunctional amine represented by the following general formula (1), and a non-aqueous solvent,
Y is a linear alkyl group having 1 to 4 carbon atoms, a phenylene group, or an oxygen atom, and each of R 1 and R 2 is independently a hydrogen atom, a methyl group, an ethyl group, a trifluoromethyl group or a methoxy group &Lt; / RTI &gt;
[Chemical Formula 4]

The method according to claim 6,
The blending ratio of the polyacrylic acid and the polyfunctional amine is,
Wherein the carboxyl group in the polyacrylic acid is 15 equivalents or less based on 1 equivalent of the amino group in the polyfunctional amine. The method according to claim 6,
The blending ratio of the polyacrylic acid and the polyfunctional amine is,
Wherein the carboxyl group in the polyacrylic acid is 1.5 to 15 equivalents based on one equivalent of the amino group in the polyfunctional amine. A method for producing the polymer compound according to claim 3,
Polyacrylic acid and a polyfunctional amine represented by the following general formula (1) are heated at a temperature of 150 ° C to 230 ° C,
Y is a linear alkyl group having 1 to 4 carbon atoms, a phenylene group, or an oxygen atom, and each of R 1 and R 2 is independently a hydrogen atom, a methyl group, an ethyl group, a trifluoromethyl group or a methoxy group Wherein the polymer is a polymer.
[Chemical Formula 5]

A method for producing the polymer compound according to claim 3,
The method for producing a polymer compound according to any one of claims 6 to 8, wherein the intermediate composition is preheated at a temperature of 40 to 140 캜 and then heated at a temperature of 150 to 230 캜. A method for producing a polymeric compound according to claim 5,
Polyacrylic acid and a polyfunctional amine represented by the following general formula (1) are heated at a temperature of 180 ° C to 230 ° C,
Y is a linear alkyl group having 1 to 4 carbon atoms, a phenylene group, or an oxygen atom, and each of R 1 and R 2 is independently a hydrogen atom, a methyl group, an ethyl group, a trifluoromethyl group or a methoxy group Wherein the polymer is a polymer.
[Chemical Formula 6]

A method for producing a polymeric compound according to claim 5,
The method for producing a polymer compound according to any one of claims 6 to 8, wherein the intermediate composition is preheated at a temperature of 40 to 140 캜 and then heated at a temperature of 180 to 230 캜. As a negative electrode of a power storage device,
A negative electrode binder comprising the polymer compound according to any one of claims 1 to 5 and a negative electrode active material,
Wherein the negative electrode active material is at least one selected from the group consisting of a carbon-based material capable of intercalating and deintercalating lithium, an element capable of alloying with lithium, and an element capable of alloying with lithium. 14. The method of claim 13,
Wherein the negative electrode active material is at least one selected from the group consisting of a silicon material obtained by decalcification from CaSi ₂ , Si, and SiO 2 _V (0>v> 2). An electrical storage device comprising: the negative electrode according to claim 13 or 14; and a nonaqueous electrolyte. As a negative electrode slurry used in the production of a negative electrode of a power storage device,
A positive electrode active material composition comprising the intermediate composition according to any one of claims 6 to 8, a negative electrode active material and a solvent,
Wherein the negative electrode active material is at least one selected from the group consisting of a carbon-based material capable of intercalating and deintercalating lithium, an element capable of alloying with lithium, and an element capable of alloying with lithium. 17. The method of claim 16,
Acetylene black,
Wherein the 50% particle diameter of the acetylene black is in the range of 0.35 to 0.75 占 퐉. A method of manufacturing a negative electrode of a power storage device,
A method for manufacturing a negative electrode, characterized in that a negative electrode active material layer is formed on a current collector by using the negative electrode electrode slurry according to claim 16 or 17. 19. The method of claim 18,
Wherein the negative electrode slurry contains at least one selected from the group consisting of a silicon material obtained by decalcification from CaSi ₂ , Si, and SiO 2 _V (0>v> 2) as the negative electrode active material A method for manufacturing a negative electrode. A binder for a negative electrode containing the polymer compound according to any one of claims 1 to 5. A method of manufacturing a negative electrode of a power storage device,
An active material layer forming step of forming a negative electrode active material layer on the current collector by using a mixture containing the intermediate composition and the negative electrode active material;
A condensation step of condensing the polyacrylic acid and the polyfunctional amine by heat treatment of the negative electrode active material layer
Wherein the negative electrode has a thickness of 10 nm or less. 22. The method of claim 21,
Wherein the negative electrode active material layer is dried and heat-treated in the condensation step. 6. The method according to any one of claims 1 to 5,
Wherein the polymer compound has a first crosslinking structure derived from a polyfunctional amine represented by the general formula (1) and a second crosslinking structure derived from another polyfunctional amine. As a polymer compound to be used as a negative electrode binder of a power storage device,
Wherein the polymer compound is a compound obtained by condensation of a polyacrylic acid with a polyfunctional amine represented by the following general formula (1) and a polyfunctional carboxylic acid.
(7)

25. The method of claim 24,
Wherein the polymer compound further has a crosslinking structure derived from both the polyfunctional amine and the polyfunctional carboxylic acid represented by the general formula (1).